In no particular order...

Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb.

Blazing Saddles.

Animal House.

The Great Dictator.

It's a Mad, Mad, Mad, Mad World.

Life of Brian. (A movie so funny, that cutting room floor clips like THIS are funnier than the finished product in most.)

Young Frankenstein.

This is Spinal Tap.

The Odd Couple.

The Graduate.