On Thursday night at Alex’s Place at the YMCA, Jim Belushi received some startling news. He was not, in fact, the mother of Island teenager Della Burke. At least that was what the audience decided. Mr. Belushi was performing with the IMPers, an Island-based, award-winning improv comedy troupe for teens and young adults. He and Miss Burke were playing a comedy game called Should Have Said. The game involved the two sitting in a car having a conversation. The twist came when every now and then the audience would ring a cowbell signaling that the actor should have finished their sentence some other way.

“We had no idea what we were going to say and the audience knew it,” Mr. Belushi said. “We were all there together, holding our breath, waiting for the next line.”

The crowd and the performers loved the show. Talking to the Gazette afterwards, Mr. Belushi described what he calls the magic, or the thrill of uncertainty and the collective relief of a witty punch line that the actors share with the audience. He said it’s the most exciting part of improv comedy.

Amy Fligor, Clare Boland, Aaron Wilson, Eva Wilson, Ashley Girard and Jared Belushi. — Ivy Ashe

“When it’s a clever line or a genuine moment, the whole room is relieved and in this really joyous state,” Mr. Belushi said.

With over 40 years of comedy experience, Mr. Belushi has an acute feel for the magic. His improv career began at age 16 with a performance at The Second City, a Chicago improv troupe that has long been the proving grounds for some of comedy’s finest.

“I was floored by the magic in that room,” Mr. Belushi said. “I said to myself, I want a piece of that. I’m coming here. What you need to understand is that Alex’s Place is built for the magic. It’s the Hot Tin Roof for teens.”

The YMCA’s teen center, which is named for the late Alexandra Gagnon, opened in 2011 with the goal of providing an engaging and safe space for Island teens. Alex’s Place hosts teen-friendly nightlife and performances of all kinds. It also offers a variety of creative workshops, including the popular Adrenaline Music Program.

The IMPers looked right at home in front of an audience of predominantly teenagers and their parents — the two age groups choosing seats on opposite sides of the stage from each other. Although the black-box theater in the basement of Alex’s Place was dark, the teen section could be identified by the light blue glow of its smartphones.

Some of the improvisations involved the audience helping to get a skit started. For one, the audience was asked to come up with a famous line from a book. A man in the crowd suggested Herman Melville’s quintessential opening, “Call me Ishmael.” A teenage girl countered with a quote from the Hunger Games trilogy. “May the odds be ever in your favor.”

The performers took the girl’s suggestion.

IMPers founder Donna Swift said she felt an immense sense of validation as she watched the group onstage at Alex’s Place. Ms. Swift said that comedy is a great way for kids to show off their smarts outside of school.

Della Burke and Jim Belushi capture the magic. — Ivy Ashe

“It’s a way for kids to use their knowledge without writing things down on a test,” she said.

IMPers usually get their start in Ms. Swift’s IMP for Kids summer programs. She said that inclusion in the IMPers requires many years of improv experience and that some of the current members have been working together for as long as eight years.

“The IMPers are an advanced group,” Ms. Swift said. “I treat them all like professionals.”

Ms. Swift’s approach paid off in April when the IMPers performed at the Chicago Improv Festival. A high honor in itself, this year’s performance represents an impressive step up from their debut as a teen apprentice group at the festival eight years ago.

Ms. Burke, one of the group’s college students, has performed at the Chicago Improv Festival four times. She said she was especially pleased with Thursday’s show and that she enjoyed working with Mr. Belushi.

“It wasn’t as nerve-wracking as I expected,” she said. “It was comfortable.”