Have you ever made the anti theft system in a store go off? If yes, were you guilty?

I've had the occasional checkpoints go off like crazy in the local grocery store, although I never stole anything and the staff was understanding or at least knew that it might happen because of the specific product tag etc.

A friend of mine had the misfortune of that mistake happening twice in the same day in different stores, both times she was searched and after the second time she broke into tears after exiting the store.