Wet prank

This is so evil. I like it!

*that's the evil eat thing I can imagine*

Dies it work?

Just like leaving a tip for a waiter/waitress you don't like

Lol, I like it. >:)

Deadly trap.

And it might create a vaccum so when he pulls hard on the mug, it goes flying and he has to clean up the mess.

'That's the most evil thing I can imagine' :')