The Big 5: Books that Made You Laugh Out Loud

What are your Big 5 books that made you laugh out loud?

We've all read them, right?  You are working through a book and you just can't contain a chuckle at a story or the way the author put something.  Any book that made you laugh is eligible, but I want to encourage you to not list too many books that are in the "humor" or "comedy" section of the bookstore.  One or two of those at most.  I'm hoping to find books/authors with a more natural humor, not just books by comedians.  BONUS: If you want to offer a short (!) quote or funny part, feel free.  But it must be funny.  If it's not funny, I will sound the gong.  Also, please don't list things like Far Side books.  These need to be reading books.  If you don't know 5, list what you have.