Yes, you heard right. The Muppets did Nirvana and it came out ...weird. If you think it's hard to imagine a combination of 'The Muppets' and 'Nirvana' you're not wrong. Still, here we are, with a cover of 'Smells like teen spirit' by the muppets. Not only that, but they decided to cover it as a barbershop quartet: four muppets singing acapella are singing 'Smells like teen spirit'. Wait, it gets even weirder.
The scene in question has the muppets kidnap Jack Black, tie him to the barbershop chair and give him a forced haircut and shave while singing. As Jack Black realizes what they are singing he shouts out "You're ruining one of the greatest songs of all times!". The scene finishes with Jack Black's head shrunk as if the whole thing was some kind of a voodoo ceremony. Apparently Kourtney Love did not love this gesture and protested against it - we can't blame her to be honest.
If you did enjoy the humor though, we highly recommend watching Dave Grohl's drum battle with Animal the muppet - Now we see who best!