Audiences can’t get enough of improvisational comedy. The popular and ubiquitous “Whose Line Is It Anyway?” has proven this over its lengthy network television lifetime.

The show, a United States spin-off of a popular British show, originally aired 1998 - 2006 on ABC and ABC Family and has found renewed interest on the CW network, which began airing new episodes of the show in 2013.

Two of the most popular cast members of “Whose Line Is It Anyway?,” Colin Mochrie and Brad Sherwood, pay a visit to Easton’s State Theatre Center for the Arts, 8 p.m. Nov. 21.

The pair, who last appeared at the State Theatre in 2014, is in the midst of their tour, “An Evening With Colin And Brad.” Audiences can expect a night of rapid-fire, audience-driven, interactive comedy.

Mochrie and Sherwood have been touring together for roughly 13 years. Fans will be delighted to hear that the pair has no plans to stop performing “anytime soon,” according to Sherwood during a phone interview. “We’ve been having a great time,” he says.

When asked why the cast continues to film new seasons of the TV show, Sherwood notes, “It’s fun to play with your friends and make each other laugh and then get paid for it.”

The nature of improvisational comedy keep the live shows fresh at each stop on the tour. The duo avoids taking the same path even if some audience suggestions or improv games are similar at times.

“When you are improvising, as a purist, you’re taking new suggestions from the audience members and doing different things and bringing people up on stage, so that keeps it fresh.“

“We may play the ‘Sound Effects Game’ every night that we do the show, but it’s doing different things and situations and scenarios,” he says.

Sherwood says that since he and Mochrie have performed at the State Theatre several times, they realize many audience members are returning fans.

“We try and innovate and come up with some new games, change things up, so that every time they come to see us, they’re going to see at least two or three things that they haven’t seen before,” he explains.

“We’ve had people come to every show that we have done in a town. For example, we play Milwaukee every year and we’ve been there I think 11 years in a row and some people have come to every single show. That’s an indicator that it’s not getting monotonous for them.”

Sherwood says some improv games are simple yet incredibly popular with audiences. So they remain in the pair’s repertoire.

“There’s one game that we play, that’s a ‘Mouse Trap Game,’ where we perform blindfolded and barefoot. The nature of that game doesn’t change much, but it’s such a crowd-pleaser that even people who have seen it 10 times don’t care because they still enjoy watching us step on the mousetraps.

“That one is sort of like a good old stand-by that we’ve just kept in the show because the audiences howl like little kids. People love it as much as we hate it. So that’s why we are still doing it,” he laughs.

People would perhaps be surprised to learn that Sherwood and Mochrie are a great deal more subdued offstage and off-screen.

“If you’ve only see me on the TV show and live, you might be surprised,” he says, “Both of us tend to be very sort of withdrawn just in our regular daily lives. We both have very outgoing wives. They’re the two jumping sprites in our world.

“For people that really like ‘Whose Line,’ to see improv live if you haven’t seen it is really a treat because then you truly get to experience that we are completely making it up,” he says of the stage performance.

“I think most people are looking at it kind of like a magic act, like there’s a secret trap door that we default to and there’s a trick to it, that we’re not actually coming up with this stuff on the spot, that it must be sort of predetermined or preplanned.

“When they see it live and either they or someone they know comes up on stage, then they truly get to appreciate that yeah, we’re just making it up and it is funny and it is possible.”

Tickets: State Theatre Box Office, 453 Northampton St., Easton; statetheatre.org, 1-800-999-STATE, 610-252-3132