http://www.tremorseven.com/aim/deepaim.php?job=view

#368: One day a beaver and a termite were walking down the road together. "I can eat through a tree with my teeth," said the beaver. "That's nothing," said the termite, "I can burrow through a tree." Then they heard a voice behind them. "You two think you're so smart, but you're nothing!" It was a bitter old drunk lady.

Just keep hitting refresh until they're funny...

This is my favourite, and interactive 404...
http://thcnet.net/error/index.php

Good collection here too if you're interested...
http://www.plinko.net/404/