Funny things are always happening around the place that used to be called ImprovOlympic, but this week promises to be an especially silly one.

A sold-out anniversary show Saturday at the Chicago Theatre is luring alumni from both coasts, all eager to crack people up in honor of the place where they learned how to do it.

The California contingent includes Austin Powers creator Mike Myers, former Conan O'Brien sidekick Andy Richter, veteran sitcom weirdo Andy Dick, "Scrubs" janitor Neil Flynn and "Mad TV" troupers Ike Barinholtz and Stephnie Weir.

Arriving live from New York is a large chunk of the "Saturday Night Live" cast, among them Rachel Dratch, Horatio Sanz, Seth Meyers and Amy Poehler. With a baby due any day, Poehler's "Weekend Update" co-anchor Tina Fey had to send regrets but promises some sort of video presence.

Dan Bakkedahl will be there, a few weeks before starting as a new correspondent on "The Daily Show With Jon Stewart." Fellow alum Jon Favreau can't make it, but pal Vince Vaughn might.

What's really funny, though, is what they're celebrating: a moment 25 years ago when nothing at all happened.

The two founders of the theater, recently renamed IO to appease trademark lawyers at the U.S. Olympic Committee, hadn't even met in August 1980. David Shepherd, a crucial figure in Chicago theater who had launched the Second City precursor called the Compass in 1955, was then in New York, pairing off improv teams in a friendly competition he hoped to spread into urban schools.

Meanwhile, in Chicago, a former teacher and radio host named Charna Halpern was taking classes at Players Workshop, an acting studio then loosely affiliated with Second City.

Their collaboration, a brief and frustrating one, would put into motion the ImprovOlympic operation that launched many big names and shored up Chicago's reputation as a comedy incubator. But it didn't start until 1981 -- 24 years ago.

"I screwed up," says Halpern, now IO's sole owner. "Someone told me it was my 25th year and I was like, 'You're sure? I don't think so.' And they were like, 'Oh yeah, this is it.' "

By the time somebody did the math, the theater was booked and the actors had cleared their schedules. So the show goes on. "It's only a couple months early!" Halpern declares.

Really, though, the growth of IO is marked by any number of milestones:

*1983, when Second City veteran Del Close signed on to teach a long-form improv structure called the Harold that became IO's centerpiece.

*1995, when the transient company -- bounced around at least 10 scattered spaces in its first decade -- settled into its own two-theater complex at Clark and Addison.

*1997, when IO West opened in Los Angeles as a place for transplants to perform and teach Close's concepts.

*1999, when Close died and left his disciples to carry on his lessons.

And in the volatile world of Chicago theater, 24 years is a rare stretch of longevity -- maybe even one worth celebrating.

"It's a real testament to Charna, who did a really good job of keeping that theater vital and alive and keeping people connected to it," Poehler says, "and it's a testament to Del, who taught us all this stuff that never gets old for us. It definitely is like improv high school."

As Homecoming Week gets under way, students and faculty alike are in the mood to reminisce.

The beginning

David Shepherd: The people who invented the ImprovOlympic were Howard Jerome and myself. We had a league in New York in 1975, and we used to play once a week. I was not interested in starting a comedy movement. I was interested in reforming the theater.

Charna Halpern: I was directing a children's show for Players' Workshop, and somebody said to me, "David Shepherd's here directing a play and you can audition." And I was like, "Nah." Then I was driving home -- this was the biggest revelation I ever had in my life -- and I started remembering a chapter about David Shepherd I read [in the Second City history book Something Wonderful Right Away] that said he started this thing with all these different comedy troupes competing.

Shepherd: There were 10 events, and each one highlighted a different dramatic skill. They had to do with character, emotion, pantomime and also basic skills like telling a story, singing a song, working with no words at all.

Halpern: It dawned on me that I could pull this off. "Oh my God, this is it. I could run ImprovOlympic." And I instantly got on the cloverleaf and came back downtown.

Shepherd: There was something about ImprovOlympic that was right for her.

Halpern: We had teams that were coming out of Players Workshop. They would come to my house and pay me 10 bucks each. I would teach them all the ImprovOlympic games, and they would join the competition.

Shepherd: We used to perform on Monday nights at Second City. That, I think, spread the word that this was something to do.

Halpern: Then I was thrown out and had to find a place right away, so I went across the street to a place called Exit, which was a punk-rock club. We had to be out of there by 10, because that's when the green-haired people starting coming in.

Shepherd: It came to be known as an affinity sport. Some rabbis would come to you and they had a team, and we'd train 'em. Or cops -- we had a group of cops called Magnum Farce.

Halpern: Shepherd is the type of person who has good ideas but he has too many of them. He never could complete one without starting another. So it was very hard to get anything done. It was like an intelligent, creative ADD. Luckily, I was smart enough to say no after a while.

Shepherd: I was not able to make any money doing this.

Halpern: So he decided to go back to New York and [work on] ImprovOlympic there while I kept it going here.

A transformation

Halpern: The teams would always fall apart after the competitions. They'd fall for the hype and start thinking, "We're s---, we lost the competition." I'd be like, "Nobody cares. Why are you fighting with each other? That's not how it's supposed to happen." And I finally got so mad about it that I stopped the whole competition aspect.

Andy Dick ("Less than Perfect"), who started IO classes in 1986: I never liked the competition part. I just wanted to do shows and have fun. It's useless, like having a competition for painting.

Shepherd: And they now have an organization [formerly] called ImprovOlympics, which has nothing to do with ImprovOlympics whatsoever. All her formats are comedy formats. She has a very interesting, strong staff there. But they don't do the ImprovOlympics.

Halpern: The shows were successful, but we were resorting to the same tricks. I thought we'd gone about as far as we could go with the games. So I was very bored with it. [In 1983] I saw Del at Crosscurrents [the now-defunct Wilton Avenue club that was hosting ImprovOlympic's shows], about the time I was really desperate to do something different with the work. I went up to him and said, "How would you like to make 200 bucks and some pot?" And he said, "What do I gotta do?" And I said, "Teach one three-hour class, like maybe tonight."

Dick: I was actually afraid of him. He was intimidating. He was bigger than life, and very intellectual. A very deep voice. And just chain-smoked like hell.

Halpern: He said he had this unplayable, unteachable thing that he had been working on since the '60s called Harold, and maybe if we put it together with some of my ImprovOlympic games we could create a form. I was like, "Oh my God, yes yes." It was a vision I could get behind. The truth in comedy, the agreement, the idea of supporting each other and making each other look good -- it all made sense.

Amy Poehler ("Saturday Night Live"), who started IO classes in 1993: Del's life was saved because of her. Really -- she said, "You're so amazing. I want to create this thing around you."

The people

Halpern: We would stand outside with passes saying, "Please see our show!" We just wanted an audience bigger than the amount of people playing. But we'd still play if we had five.

Andy Richter ("Quintuplets"), who started IO classes in 1988: There was sort of an unofficial rule: If there were more people on stage than there were in the audience, then we wouldn't do a show.

Halpern: Andy was very smart. He was always counted on for a one-liner. He's one of those people who could stand there in a scene and not say anything, and then say something and just hit you over the head.

Richter: Improv songs -- I just f---in' hated that. There's only so many times you can do rap. The big joke is Oh, you're a WHITE GUY! Doing RAP! It's just boring. And I was bad at it, too.

Halpern: They all hated [the music]. But I forced them to do it anyway because watching them suffer through it was so much fun.

Dick: We would mix teams up all the time. I remember Chris Farley, Mike Myers -- those were the big ones. If you were there long enough, you eventually played with every single person there at least once. It was just a big family of performers, a giant circus family.

Halpern: [Del and I] met Myers in Canada. Mike was on the Second City mainstage there, and he was very funny and very brilliant. He really took to Del's work. He hung out with us afterward, and I said if you ever come to the States please call us. And he did. He couldn't work [at Second City] for a while because his Green Card didn't go through, so he started taking classes and performing in our shows. He just played whenever he wanted to, which was pretty much all the time. And he never missed a class.

Mike Myers ("Austin Powers"), via e-mail: The audiences were very hip and the other performers were very talented and dedicated to the purity of improv. I loved that there was no makeup, no props, no learning of lines. The only preparation was to get into the right frame of mind.

Dick: [Myers] was incredible, even back then. Just a whirlwind of energy and characters. He was one I looked up to, like: Wow, that guy's just got a f---in' trunk filled with characters that seems bottomless.

Halpern: Farley was the wild hair. Farley could be counted on for energy and craziness onstage. He certainly wasn't a cerebral player, but he was an emotional player and a physical player.

Poehler: He was exactly what you'd expect -- a huge force, with crazy energy on stage, and the audience loved him.

The places

Richter: It was Charna, and her dog Gracie, and Del, and that was about it. And wherever they could get space. In fact, I think one of the reasons I ascended so quickly in the ranks of ImprovOlympic was because I had a pickup truck and Charna always needed something moved.

Tina Fey ("Saturday Night Live"), who started IO classes in 1993: The Wrigley Side [then IO's base, a bar near Wrigley Field] was a good space and had very good chicken fingers. Jeff Richmond, my husband, was the piano player at the time and he used to have to park his car by Wrigley Field either on a game night or in the middle of freezing cold winter, and then, like, haul two huge keyboards a few blocks, up the stairs to Wrigley Side, play for two Harold shows, and then hurry and pack up all his stuff before the blues band went on. And then he made, like, $25.

Poehler: I was there to open the current space [3541 N. Clark], and it was great, because people were breaking down walls and painting the stage and cleaning up the green room. If you clean the toilet at a theater, you really feel a part of it.

Halpern: I remember having panic attacks when I signed the lease to this space. At the time the rent was, like, $12,000 a month. And I was like, "I'm lucky if I make $50 a week. This is insane!" If anyone had told me they'd be lined up outside the door, I never would have believed it.

About Del

Myers: He was a series of contradictions. He had an encyclopedic knowledge of comedy and had the air of a very rational librarian, and yet he was also into the world of the supernatural and spirituality. In his classes, he was in total command but never total control.

Richter: He wasn't shy about saying "You're boring me. You're doing it wrong."

Poehler: Everyone needs the grouchy, iconic leader to talk about. He was incredibly interesting and a kind of living genius.

Fey: The best thing with Del -- and it's a trap you can fall into at Second City -- is that Del would not allow any sort of cuteness in your work. It all had to be honest, at the top of your intelligence or higher. I think people get bad habits of being cutely entertaining, if they don't get that beaten out of them.

Poehler: I still don't know if he f---ing remembered my name. I think he just called me The Blonde One.

About Charna

Fey: I love Charna. She is this scrappy, abrasive at first but really, really goodhearted, very loyal woman. People have one set of feelings about Second City, where they worked and probably got paid, and for some reason a more affectionate set of feelings about ImprovOlympic, where they paid [for classes] to get on stage.

Richter: Back in the day, there were a lot of people who had a problem with her because she would move them around to different teams and pull them from teams. But most of the people who would get pissed like that were not very good improvisers. Charna was pretty good about spotting talent and elevating talent and keeping talent fairly happy.

Dick: When you'd have so many -- and I'm talkin' hundreds -- of such creative minds stewing together, you've got to have that voice of reason. And that would be Charna.

Poehler: She's like everybody's mama. If we were all struggling rock musicians, Charna would be the one making sure we all ate and making sure we all went to our gigs.

Dick: And she's Jewish. I don't know how that helps, but I'm sure it does.

Lessons learned

Richter: Don't pander. Del would say if you treat your partners onstage as if they were poets and artists they will respond in kind. They will act like poets and artists.

Dick: Don't dumb it down for the audience. Throw out the first and second choice in your head, and go with your third or fourth or fifth choice. Keep it real. Pull from your own experiences.

Myers: As Dr. Evil [one of his roles in the Austin Powers movies], there's tons and tons of improv, and that improv was shaped by every improv experience I've had.

Richter: At my peak I was doing what ultimately ended up, like, nine hours of improv every week or more. Once you get on stage not knowing what you're going to say or do, and you entertain people for an hour and a half, you really do feel like you can do anything. That's always stuck with me. When anybody complains about having to act, I think, "Jesus Christ, somebody's already written the words for you. You know what you're going to say."

The anniversary show

Halpern: I think we'll keep advancing the anniversaries. In three years we'll do the 30th. That way I can do the 50th before I'm too old to enjoy it. We'll be older than Second City in less than 10 years.

Poehler: For me, this anniversary is a good way of everybody getting back together and remembering not who everybody has become, but who everybody is and was. It's not like a night of stars! It's a night of improvisers. We all knew each other when, we all dated each other, did drugs together and went to each others' s---ty apartments and rehearsed in each others' s---ty basements and coached and taught each other. It's amazing that most people who will be at the theater still are really good friends.

Dick: It's gonna be fun, man.

Darel Jevens was an ImprovOlympic student sometime between the eras of Andy Richter and Tina Fey.