Blue Man Group celebrates 25 years.

If you have never seen Blue Man Group, you are probably curious just what it is. And if you have, you probably still have trouble describing this mix of music, theater, technology and improv.

"Someone will come to see the show, and then they'll go and they'll see their friends they'll say, 'We went to see Blue Man.' 'Oh Blue Man, what is that like,'" says Christopher Bowen, Blue Man Group's associate creative director. "They'll be like, 'Well I don't know. I don't know quite how to explain it but it was amazing.'"

The Blue Man character is more easily defined.

"He's a stranger, he's an outsider and he's exploring the world," says Bowen.

To better understand it, NY1 went behind the scenes at their training center in the East Village, not far from where they perform at The Astor Place Theatre to check out some of their newest instruments, like the Tone Mill and the Deconstructed Vibraphone.

"We change the show; we change the instruments," says Randall Jaynes, director and Blue Man." It's all about connection. We are trying to reach out to the audience and get them to connect to each other and get them to connect to us."

"We have the audience up there and they're part of the show," says creative director David Steele. "They really define how much fun the show is going to be. They are the fourth Blue Man, that's the way we've always looked at it."

So why blue?

"It seems a friendly color," says Bowen.

In addition to all of the new instruments, there is still the classic quintessential PVC.

"Basic PVC pipe you can get at any hardware store, says Steele." You whack on one end and sound comes out the other end."

Well they did say the audience is the fourth Blue Man.

The show has performed across the country and around the world. There is a new book out chronicling its history. And most importantly, they're always looking for a Fourth Blue Man.