You're never too old to prank call a store. Be sure you get the manager himself.
Also, I'm sure they have public restrooms. Toilets get clogged.
If you really want to fuck them over, print up "50% off your next HH Gregg purchase" coupons and slap 'em on a few hundred car windshields around Black Friday.
Then call the grocery store that's hiking up the prices on steroid-induced milk and chicken and ask them if they have Prince Albert in a can or King Edwards in a box.
Dial up the bowling alley next--you know what to do with 18-pound balls.
Finally, it's the bar that charged you $9 for a .75 margarita: "Is Mike Rotch there? How about Mike Hunt?"