T-Shirt Laundry has an awesome Harry Potter/Dirty Harry mash-up parody t-shirt for sale. Here is the official description.
Police Inspector “Dirty” Harry Potter is a hot-headed rookie fresh out of the Hogwarts Police Academy. His first assignment is a sadistic serial killer known only as “Voldemort”. Dirty Harry will stop at nothing to solve this crime even if it means roughing up a few muggles along the way.
The t-shirt is available in a variety of colors, on sale for only $11 plus shipping (normal price $16). And I’ve discovered that they are offering 20% off with the coupon code “THANKS”, enter at checkout. Thanks to /Film reader Dan M for the tip.