You simply must read this if you like pranks … in this case, with a serious security background. (via BoingBoing)

This prankster started signing his credit card receipts in all sorts of unusual ways (scribbles, heiroglyphics, grids, etc.). The employees handling the transactions didn’t care one whit. They didn’t even look at the signatures.

I particularly like his glueing on the "we watch out for you" add instead of a signature.