1.    Jump out from behind shelves, displays, etc. and yell, "Peek-a-boo!" at people.

2.    If someone asks where something is, say, "Oh, is THAT what you call it now?" ::wink wink::.

3.    Walk up to the employee at the register and say, “Hi, How may I help you?”

4.    If you are an employee: after scanning everything, ask the customer if they want fries with that.

Six undercover actors burst into song in a grocery store in Queens. Three minutes and lots of silly choreography later, they returned to their roles as shoppers and stock boys. The mission was filmed with hidden robotic, lipstick, and wearable cameras. The song was played over the store's PA system live.