626
Place packages of gum in people's carts. Don't let them see you and they might purchase them!
627
Spill water (or another fluid) all over the floor. Then grab a wet floor sign. Take a Sharpie, cross out "Wet Floor", and write "THIS IS SPARTA!".
628
Enter the electronics isles, and repeatedly ask the cashiers where the toilet paper is.
629
Slap the little black bar codes found in games/DVDs to the undersides of peoples' carts. Let them walk through the security gates.
630
Shove your friend or yourself in the dog food shelves, and jump out at people telling them it tastes good.
631
When someone isn't supervising their cart, hop inside it. When they ask you to get out, ask them if you can eat/wear their merchandise. Don't exit the cart. See what they do.
632
Make a little man-cave out of the 12 pack soda boxes, like in the movie Employee of the Month. Stash some food and even a couple lawn chairs or table up there. See how long it takes for someone to notice.