One joke that we did in residence was the Chinese Fire Drill, I don't quite know why it is called that. Anyway..
The victim is on the pot in the dorm washroom. Everyone grabs a bucket (we used the waste baskets from our rooms) and fills the buckets with water. Take a paper bag and set it on fire, toss it under the door into the stall. Yell fire as everyone tosses the water into the stall. Needless to say the fire as well as the victim get very wet.
This one fellow in the house was hit a number of times and took to relieving himself in other locals. We followed him a couple of times and nailed him in many parts of the residence.
Later of course we conspired with our victim to get back at the original instigator of the drill. The guy in the stall had a bucket of water, and when the the instigator tossed the bag in we all hit him.