What's with Andy?

Bluebeard's Crate (2x21)

Air date: Feb 18, 2004

Andy finds out about a prank contest in his prank magazine (Prankster Weekly), in which you have to use nothing! Andy sets up his prank,a gigantic box,in which there is...nothing! When the prank magazine guys appear, Andy finds there is junk in his box instead of nothing, but who did it?