ROTFL! These are great!
Short-sheeting is pretty easy to do. You take the flat sheet off your victim's bed. Tuck the bottom of the flat sheet into the top of the bed, as if you were making the bed upside down. Then fold the free end of the sheet back up. The bottom of the flat sheet should look like the top of the fitted shset. Then, put the blanket/comforter back as it was. Looks like a nicely made bed until you try to get into it.
Here is a good one: There was a pretty obnoxious freshman one year living on a particular floor in my dorm. So one day, his floormates relocated his room. Onto the river. The Charles River basin freezes solid enough to support a significant amount of weight during probably 4 winters out of 5. So 5 or 6 of this guy's floormates took his school-issued bed, desk, and chair out onto the river and set up a "room" for him. Made the bed with his sheets, gave him an empty keg for a nightstand, etc. People still joke about the "room with a view"