One quick way to get yourselves in trouble, or even hurt, is to pull off a prank that seemed harmless at first, but not for the victim. For example, this person decided to use Elmer’s glue to create a fake milk splash, and then proceeded to place it on a MacBook Pro.
Official Source: http://www.pleated-jeans.com/2013/11/14/there-are-pranksters-among-us-21-pics/