When I was in nursing school, people were stealing food out of the refrigerators in the dorm. (This was 50 years ago, it's hard to believe it's still a problem!) Anyway, we got our revenge. We baked a gorgeous, chocolate cake with beautiful chocolate frosting. Nobody but us knew the secret--it was loaded with Ex-lax! We even went so far as to take a slice out, to make it appear totally innocent! Never knew who, but we knew we got 'em!