This prank doesn't need anything but a friend who understands dirty jokes and yourself.

You: Okay, say the word 'addicted' every time I pause, alright?
Friend: Okay.
You: Money...
Friend: Addicted.
You: TV...
Friend: Addicted.
You: Candy...
Friend: Addicted.
You: Hitting people in the face with an iron...
Friend: ...addicted...

By this point Du need to come up with several different others to get them to barely even notice what they're "addicted" to.

You: Soda?
Friend: Addicted...
You: What hit Du in the face last night?
Friend: Addicted...

The look that will come over their face will be absolutely priceless.
Try it out!

-Ray