I love the Monty Python sketch where Terry Jones goes into a police station to report a crime but the officer on the front desk (John Cleese) can only hear him if he's spoken to really loudly, he then changes shifts with Chapman who can only hear him if he's spoken to with a deep voice, then Eric Idle enters as another officer and he can only hear people if they talk really quickly, then John Cleese returns because he forgot something and they all have a conversation with each other without missing a beat on when to speak quickly, loudly, etc.
Cracks me up every time.
Monty Python had some great stuff in the early years, the impressionist painters bicycle race, that crazy job interview where John Cleese is ringing that bell, the 'Gala Luncheon' sketch, I could go on.
Did anyone ever see Jam, the sketch show by Chris Morris? That was some seriously weird stuff.