Climb into a washer/drier/refrigerator and

a) wait for someone to open it up and move it

or

b) wait for someone to pass by

And pop out and scare the shit outta them. Preferably with a loud, catchy catchphrase >.>

Enter in full combat cosplay uniform, bang your foam sword on your foam shield, and yell "I AM THE KNIGHT OF FRED MEYERS! I WILL SLAY YOUR DRAGON KING OF WALMART! YAAAAA!", charge towards the manager's office and attempt to outfight any security along the way.
^ bonus points for recruiting 3+ little kids to join the initial charge and try to fight any walmart employee along the way.

Trip a walmart employee when another customer is walking by and scream "SHE DID IT!" bonus points for elder employee, female passerby (I dunno, and really, it doesn't even matter, just stick with the pronoun whatever you get) and waving a hammer as you make your accusations.