Transcript for 'Muppets Most Wanted' Stars Have a Good Laugh
"Nightline" and the muppets have a longstanding, beautiful friendship which began under this show's founding anchor, Ted Koppel." You're looking very wall Street indeed, if I may say so. I tried to wear my more dapper stuff to look as good as you. I have rather seen a more dapper looking frog. The muppets have a new movie coming out. We sent nick watt to interview the stars. Take a look at what happened next. I want you to travel the world, show a global international audience what you can do. Here it is, the muppet movie. I was to ask some questions and answer the question what makes the muppets still funny after 20 years in show business. To shoot a movie with Kermit is a dream come true. It's fantastic. One, because I hate human actors. Kermit is good. It's not easy being me. A plan is hatched to take Kermit's place on the world muppet tour. Kermit the frog here. And their evil manager, Ricky Gervais. Dominic bad guy? It'sunce pronod "G." My name will go down in history as the greatest of all time. They're sporting a wonderful French accent. Here's my real badge. You must have been looking at the wrong badge! Kermit end us up with the gulag where Tina fey is the guard. You feel it. He's a listener. I just love Broadway. But you're right, Kermit, as ever. Your Russian accent must have taken you months to perfect. I didn't actually perfect it until about four months after we stopped shooting. Reporter: Kermit and piggy end up at the altar. Will they, won't they? Will they? Won't they? Frankly I find your INT interspecies disgusting. Clearly it's against nature, clearly which is why they never fully -- it would be an abomination of nature. The movie was great. The interviews didn't go so well. You've done nothing in this interview, you've let it all down. And it was a great interview. Really? What did he do? Nothing. I feel that I've brought the best out in you. Well, that's a skill. I'd have been better with an empty chair there. You're going to have to shape up, all right? This is "Nightline." Just up it a little bit. Come on. Oh, man. Okay. So why are the muppets still funny? Good grief. I think it's almost like a magic trick about how you make something that's actually funny for adults and that kids love. They have great timing and they're not sugary. Nothing is Dora but there's a little more going on with those guys. Why are they so funny? Because they're up with the times. Sean "Puffy" coombs. The muppets made six movies in 20 years, then took a 12-year big screen hiatus before coming back in 2011 with "The muppets," a big box office success. Your next movie, next adventure, what else can we possibly see from you guys? I don't know. I think we did it all in this movie. You're going to have to see this movie because this might be it, the end. You mean I've been in show business for like 60 years and this was the ender? Go see it, all right. We'll do another movie, of course. The cameras are still rolling. Do you understand? Yes. Yes, I understand that. I understand television, thank you very much. Of course they started on TV back in 1955. I think watching "The muppet show" was the first exposure I had to any kind of sketch comedy. And Tina fey went on to become one of the greatest comedic voices of our generation. I've always been a fan of the muppets for about 35 years. When we walked into the room, he was such a big fan, we almost couldn't shoot. He was walking around laughing really loudly. Laughing and gawking and kind of drooling a little bit. Flawlessly executed. Bravo. You're essentially a prop in this movie if you're a human. He kept putting his finger in my mouth. Yes, yes, I do not like that. I do not know where that man's finger has been. You feel as an actor appearing in a movie with muppets is a step up for you? Oh, yes. Growing up they were sort of like the most amazing comfort food. I don't have that many memories as a kid of something we would actually all watch at the same time. With the muppets, there was something for everybody. I liked Tina fey's outfits. I'm not qualified for this. Lights out! You have to wait until I'm like out of the hallway. This is like a breakdown. You're wearing stripy so stripy socks. Do you want to have a beer? Watch this movie. It's all the escapism you will ever need. I would have been better with an empty chair there. He was only joking. I'm nick watt for "Nightline." ? By the way, "The muppets most wanted" opens on the 21st. And we will be right back.
This transcript has been automatically generated and may not be 100% accurate.