Copper is toxic.

My cousin Larry used to work at a bank and had a foolproof way to steal. Whenever someone wasn't looking, he'd swallow pennies. The bank hardly kept track of them, because who would steal them anyway? Every day He'd manage to steal like 20 bucks worth of pennies at least just by swallowing them. Of course getting them out of the toilet was a problem, but he built a system for washing them out.

The only problem was that swallowing all that copper gave him a stroke, and now half of his face droops down and he can't talk right. He started swallowing quarters to pay the doctor bills, but they caught on to that.