Say THERE'S A BOMB IN WALMART EVERYONE RUNNNN. Trust me it will get you kicked out and banned for a week
Hide in one of those round clothes racks and when someone starts looking through it go "Welcome to Narnia" in a witchy whisper. Buy a lot of Skittles and go hide right behind one of the trashcans outside next to the door and when someone walks by go "TASTE THE DARN RAINBOW!"
go to the LEGOs and open a few boxes, mix some LEGO sets together. And then complain to the manager that u didnt get a mashed up Lego set. (i.e a house-car, a pirate-rocket)
Take some of the nerf guns and and have a nerf war with your friends or just go around shooting people with them
Bring in a megaphone and a recorder. Find people saying embrassing things. Record it discertly. Ask for their name. And announce
Ask for the manager and kick him/her in the crotch and run away whooping like zoidburg in Futurama i got arrested for that