A bunch of us were sitting around discussing this recently...I can't say I did much besides psyching out my younger siblings. Like if my sister made tea, I'd hide it while she was putting the tea up and then she'd freak out because she'd lost it, never knowing what really happened. And she doesn't to this day!
However, the worst thing anyone told the other day was that he got tired of listening to his brother yap so he stapled his lips shut.

Any more shocking stories?