There's a persistent story that Van Halen had a clause in their standard stage contract saying that the dressing room must contain a bowl full of M&Ms, with the brown ones taken out, or the show would be cancelled. And that one time they did find some, they did huge amounts of damage.

This is very nearly true, in fact. But there are two clauses, not one, and it wasn't strictly the band that did the damage. (http://www.snopes.com/music/artists/vanhalen.asp)