THREEDEGREES

Plastic Force Field
Use plastic wrap to block a doorway. When your victim opens the door and tries to walk right through. He will just end up bouncing back into the room he came from.

Early Morning Bucket of Water
Balance a nearly full bucket of water against someone's door at night. When they open it the next morning it will fall and flood their room. Even better against elevator doors.

Recessed Door Prank
If the victim has a recessed door, fill the area flush with the wall (perhaps with drywall) and paint to match the wall. Victim returns to a wall where the door used to be.

Leave A Door Trail
Take a person's door. Leave a trail of clue's as to where to find it. Have them running all over the place trying to find it and have them end up somewhere near where they started. (like in the next room)

Bang Snaps
Place "Bang-Snaps" in precarious positions on a door so that they will drop and explode when the door is opened. (such as balanced on the doorknob)

Brick It Up
Brick up the entrances to a building at night before anyone arrives.

Reverse Peep Hole
Reverse the peephole on peoples door. Allows for some interesting spying since very few people actually check this part of the door.

Reverse Door Knob
Remove someone's doorknob and reinstall it with the lock on the inside. Works best if the victim is in the room and the door is locked and you have his/her keys.

Clear Tape Prank
Place clear tape across the outside of a door from top to bottom. Frequently people will run into it especially if they are in a hurry. If the door is metal and has a metal frame, weld the person into (or out of) their room. Can be done to the hinges as well if there is no metal door.

Penny Jam
Jam so many pennies between the door and the door frame that the person cannot turn the doorknob to get out. Even better if the pennies are superglued in place to prevent removal. Also you may wish to put vaseline on the inside doorknob to prevent them from being able to turn the knob.