I posted this on the other thread - but your messing "with other people's heads" told me I had found a kindred spirit.
Try using Sacajawea dollars at the McDonald's drive thru. I handed the girl five coins (and they're gold in color, mind you) and she says, "This is only a dollar twenty-five." I told her to look again - she had to call the manager, he came over, started laughing and told her that it was "real money, worth a dollar each." I got a couple free apple pies for the inconvenience.
My grandfather used to carry a pocket full of Susan B. Anthony dollars around just to agravate the store clerks. They usually had to call the manager for help.