Not able to post video, so I'll just mention a couple:
It's a mad, mad, mad, mad world - most every scene is brilliant, but the standout for me was Jonathan Winters chasing Phil Silvers and finally finding the giant W.
The man with two brains - where's my hat?
Mr. Mom - when he's at the grocery store, and when he's figuring out why he won't sleep with their friend Ann Jillian (she was a hottie back in the day).
Liar liar - when he's in the elevator (all the out takes at the end).