I linked a QuickTime version of this a while back, but I found it today on YouTube: the classic "Mahna Mahna" skit from The Muppet Show.
To me, this one skit perfectly illustrates the utter genius of Jim Henson and company in the 70s. Here we have two pink muppets who seem female, although there's not really anything that indicates them as such (unless it's just that they're pink and they have giant eyelashes), singing a jazzy little tune -- and then in wanders a hippie-looking muppet with a beard, wild-ass hair, and shades for eyes, who tries repeatedly to derail the jazzy tune with something more rock-like, only to be worn down as the two pink ladies just look at each other and shake their heads every time the hippie breaks into his scat singing.
What gets me is that these two pink ladies, aside from being able to flex their mouths for enunciation of their song (whose one word is "doot"), have absolutely no other means of expression or movement. Their arms can't move, their eyes never waver from a bug-eyed stare -- and yet their reactions to the wandering hippie are always clear. It's all achieved through nothing but the way the muppets are moved by the "muppeteers". The humor of the sketch is achieved entirely through body language.