The Starbucks Prank

-Plastic Wrap
-Starbucks
-Cup

Pour the coffee into the cup. Cut the bottom of the Starbucks cup out and put in the wrap. Put the coffee back in and put on the lid. Cut away the excess wrap.

When the victim unscrews the cap, coffee will spill all over them. Why? The plastic wrap is only held by the lid, and if they can't drink the coffee from the lid, they will have to remove it. This will release the suspended plastic wrap, and since the cup has no bottom, the wrap will fall away and the coffee will be released from the plastic wrap.