None of these are by MCs, but I like em..

"You don't appreciate a lot of stuff in school until you get older. Little things like being spanked every day by a middle-aged woman: Stuff you pay good money for in later life."
Emo Philips.

"Death is one of the few things that can be done as easily lying down. The difference between sex and death is that with death you can do it alone and no one is going to make fun of you."
Woody Allen.

"I wouldn't mind dying - it's the business of having to stay dead that scares the shit out of me."
R. Geis.

"Death does not concern us, because as long as we exist, death is not here. And when it does come, we no longer exist."
Epicurus.

"Those are my principles. If you don't like them I have others."
Groucho Marx.

"The nice thing about being a celebrity is that if you bore people they think it's their fault."
Henry Kissinger.

"Experience is the name every one gives to their mistakes."
Oscar Wilde ('Lady Windemere's Fan' 1892).