I've never been much for practical jokes. At least not pulling them. My mind just doesn’t come up with things that way.
When I was in college there was one great practical joke that I heard of. In my Freshman dormitory, Wig Hall, someone had the doorway to their room removed.
They were away for the weekend and one of their friends, who had planned this meticulously, got drywall, paint, plaster, etc and drywalled over his doorway. When he returned his room had disappeared. A classic bit of nuisance.
Several months ago this clip was floating around the web. If you haven’t seen the Yankee Proposal prank, check it out.