Walk by the little mini light weight jello boxes and just slam your arm into them and run away as fast as possible....
monitor them stacking back upright and immediately do it again until caught
1. Make a fire. (Preferably where there's a load of people around for maximum fun)
2. Carefully place an egg into the fire.
3. Run somewhere where it won't get you, but close enough for you to be able to see the egg explode.
4. Wait until it explodes.
Based on something someone I know did IRL. Though they didn't do it in Wal-Mart or any kind of shop. (We have Asda over where I live, not Wal-Mart)