When you're in jail, a good friend will be trying to bail you out. A best friend will be in the cell next to you saying, 'Damn, that was fun'.

One morning I shot an elephant in my pajamas. How he got in my pajamas I'll never know.

Those are my principles, and if you don't like them...well I have others.

Life is a whim of several billion cells to be you for a while

I could dance with you till the cows come home. Better still, I'll dance with the cows and you come home."
Groucho Marx was never one to pass up an opportunity for a play on words and this occurs in his dialogue of the 1933 film Duck Soup:

If a black cat crosses your path, it signifies that the animal is going somewhere.