Re: Books that made you laugh out loud.
 

A Confederacy of Dunces

Re: Books that made you laugh out loud.
 

Confederacy of Dunces (John Kennedy O'Toole) is a good suggestion. Anything by Nick Hornby as well, with the exception of Fever Pitch.

Re: Books that made you laugh out loud.
 

The Great Shark Hunt is easily the funniest thing ever written. (The piece, although some of the Nixon articles in the book are really funny as well.)

Re: Books that made you laugh out loud.
 

Don Quixote by Miguel de Cervantes

Cervantes describes Quixote’s growing obsession with knight-errantry, saying, “he so immersed himself in those romances that he spent whole days and nights over his books; and thus with little sleeping and much reading his brains dried up to such a degree that he lost the use of his reason” (Book 1, Part 1).

Re: Books that made you laugh out loud.
 

Home Land by Sam Lipsyte has some great lines.

Re: Books that made you laugh out loud.
 

I highly recommend A Supposedly Fun Thing I'll Never Do Again, by David Foster Wallace. The title essay alone is worth the price of the book. Hysterical, and the guy's a great writer to boot.

Re: Books that made you laugh out loud.
 

Theory Of Poker.

That David S. is one crazy cracker.

Re: Books that made you laugh out loud.
 

Vonnegut. Cat's Cradle and Hocus Pocus specifically.

EDIT: also Survivor by Chuck Palahniuk. For a small sample check out his short story "Guts" (linked below) - not for the squeemish (but definitely funny... sort of).

He also wrote Fight Club.

GUTS

Re: Books that made you laugh out loud.
 

Off the top of my head...

Eat the Rich and Parliament of Whores by PJ O'Rourke.

Little Green Men by Christopher Buckley

Re: Books that made you laugh out loud.
 

Anything by David Sedaris