I liked this so much, I shared it with friends on another forum.
I found out, someone decided 15 wasn't enough. From
here :
FIFTY Fun Things to Do at Walmart(I edited out the ones Missy already covered
)
1. Take shopping carts for the express purpose of filling them and stranding them at strategic locations.
2. Ride those little electronic cars at the front of the store.
4. Start playing Calvinball; see how many people you can get to join in.
5. Contaminate the entire auto department by sampling all the spray air fresheners.
6. Challenge other customers to duels with tubes of gift wrap.
7. Leave cryptic messages on the typewriters.
8. Re-dress the mannequins as you see fit.
9. When there are people behind you, walk REALLY SLOW; especially in thin, narrow aisles.
11. Tune all the radios to a polka station; then turn them all off and turn the volumes to "10".
12. Play with the automatic doors.
13. Walk up to complete strangers and say, "Hi! I haven't seen you in so long!..." etc. See if they play along to avoid embarrassment.
14. While walking through the clothing departments, ask yourself loud enough for all to hear, "Who BUYS this junk, anyway?"
15. Repeat Number 14 in the jewelry department.
16. Ride a display bicycle through the store; claim you're taking it for a "test drive."
17. Follow people through the aisles, always staying about five feet away. Continue to do this until they leave the department.
18. Play soccer with a group of friends using the entire store as your playing field.
19. As the cashier runs your purchases over the scanner, look mesmerized and say, "Wow. Magic!"
21. Move "Caution: Wet Floor" signs to carpeted areas.
23. Test the fishing rods and see what you can "catch" from the other aisles.
24. Ask other customers if they have any Grey Poupon.
25. Drape a blanket around your shoulders and run around saying, "....I'm Batman. Come, Robin- to the Batcave!"
26. Toilet paper as much of the store as you can.
27. Randomly throw things over into neighboring aisles.
28. Play with the calculators so that they all spell "hello" upside down.
30. When two or three people are walking ahead of you, run between them, yelling, "Red Rover!"
31. Make up nonsense products and ask newly hired employees if there are any in stock...i.e. "Do you have any Shnerples here?"
32. Take up an entire aisle in Toys by setting up a full scale battlefield with G.I. Joes vs. the X-Men.
33. Take bets on the battle described above.
34. Nonchalantly "test" the brushes and combs in Cosmetics.
36. Hold indoor shopping cart races.
38. Attempt to fit into very large gym bags.
39. Attempt to fit others into very large gym bags.
40. Say things like, "Would you be so kind as to direct me to your Twinkies?"
41. Set up a "Valet Parking" sign in front of the store.
42. Two words: "Marco Polo."
43. Leave Cheerios in Lawn and Garden, pillows in the pet food aisle, etc....
44. "Re-alphabetize" the CDs in Electronics.
46. When someone steps away from their cart to look at something, quickly make off with it without saying a word.
47. Relax in the patio furniture until you get kicked out.
49. Pay off layaways fifty cents at a time.
50. Drag a lounge chair on display over to the magazines and relax. If the store has a food court, buy a soft drink; explain that you don't get out much, and ask if they can put a little umbrella in it.
*BONUS* Attempt all of the above during the same visit. 
