18.. Bring a friend and a stopwatch. Get carts and race around. every time you nock something over, subtract a second from your time. You usually get kicked out before you figure out who won.
19.. Put a squirt gun in a stuffed elmo's hand and scream, "Everybody down!! Elmo's got a gun!"
20. Get a batman costume, put it on, and run around the store screaming at the top of your lungs, "COME ROBIN! TO THE BATMOBILE!"
21. Pay for your stuff with all pennies, and then come up one too short.
22.. Randomly wlk up to some guy and say "Oh my God! I haven't seen you in forever! Why didn't you ever call me?" and see how long it takes them to figure out that they dont know who the heck you are