Can all you cleaver people help me?

I am giving a BD scavenger hunt for my daughters 18th. She and her friends will be aboard a limo-bus that will take them to different locations to find clues. One of the places they will be going will be the mall. I need to give them a clue that will lead to the information desk at the mall to receive their next clue. The clue needs to be in the form of a riddle. (I would like the riddle to have something that refers to hip hop, hip hop lyrics or hip hop rapper. something all teenagers would know) I can't think of anything, can you?