Booby trapped!

Dealing with a refrigerator bandit at work can be frustrating!  One woman who was sick and tired of having a co-worker take regular nips from the milk bottle she stored in the office fridge got even by posting a note that read, “Good morning, To whomever has been enjoying my coffee creamer all week… Surprise!!! You’ve been drinking my breast milk. Hope you’ve enjoyed – cheers!”  Have you ever had to set a booby trap for someone?  If so, what caused you to take action?