Winter Time Prank
place extremely large snowballs in front of the doors.

Knock Knock Garbage Spill
Fill a garbage can about one third full. Lean it against your victim's front door. Knock or ring the door bell and run! Find a place to hide, either behind a car or bush so you may watch the prank take place. When your victim opens the door, the garbage can will fall inside and cause water to spill inside the house.

Out Of Order
Place an 'Out Of Order' sign on an elevator door. This will cause people to take the stairs even though the elevator works fine.

Hotel Door Prank
While staying at a hotel, walk down the hallway and look for door signs that read "Do Not Disturb" and simply flip it around so it reads "Maid Service Please"

Porn In The Elevator
Tape a picture that is socially unacceptable to the inside of an elevator. Use alot of clear tape and make it very difficult to remove. Most people that would be offended by it will try to remove it, find it difficult and just move on since elevator doors open and close quickly and you must leave or else it will go back down or up. Feel free to ride it up and down a few times yourself to see what peoples reactions are.

Nameplate Swap
Swap door namelpates with office suites from down the hall or on another floor. Most people won't notice until someone who is suppose to meet with them cannot find their suite.

Buck Naked And Cold
While your victim is in the shower. Quietly open the door and steal his clothes/towel from the hanger. Your victim will be freezing cold and buck naked and won't know what to do.

Door Jam Prank
While your victim is in his room with the door shut. Jam a chair under the outside knob using the back of the chair. This will lock him inside his room until someone else lets him out.

Automatic Locking Doors
Some doors that automatically lock whenever they are closed can have the hole that the padlock bar goes into clogged. Just stuff it the next time the door is open. Then when your victim leaves and closes the door. It won't 'auto' lock, instead it will be open for anyone to go in and out as they please.

Seal A Door Shut
Squirt a can of expanding polystrene foam under a door. When the foam expands it will get hard and make it very difficult to open the door.