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.