A couple of my faves have already been mentioned, but I have two more, both from Soap. (You’re not the only one, superbee.)
Burt gets really smashed and somehow ends up standing on a coffee table. He can’t seem to step down without losing his balance, so he keeps half-stepping and then stepping back. Impossible to describe well, but man, was it funny.
Burt is running for sheriff and tells Danny he can be a deputy. They sit on two chairs and pretend they are in a police car, complete with sound effects.
I just thought of another one, from Family Ties, also with pretending to be driving while sitting in chairs. Jennifer doesn’t want her dad to teach her to drive (because he gets so tense), but he insists. So he sits the whole family down in the kitchen chairs so Jen can pretend to drive by way of a first lesson. She does it like a maniac, describing whipping around corners and jumping an open drawbridge, and the whole family leans and jumps in time with the motions. She finally stops, and Steven swears he’ll never get in a car with her again.