1. Turn all the radios on to a metal station, turn them off, then move the volume dial all the way up.
2. Fill a shopping cart with an awkward item (you know) and walk around the store. Or switch it with someone else's cart.
3. Slip various items in to carts.
4. Pick up a stuffed animal, and every time the PA system comes on, clutch the animal and rock back and forth in the fetal position, crying and saying 'The voices won't go away!'
5. Walk up to a random person and say 'Hey, how have you been!? I haven't seen you in forever.' and see how far you can make it go.