Put a fan in the window, and if possible, put another fan somewhere else in the room to keep the airflow towards the window. Put a damp towel over the crack of the door. If the smoke detector is sensitive, cover it with tape. Spray ozium or frebreeze occasionally while you're smoking, but don't over do it or else the smell of the air freshner will leak out into the hallway and give you away. Never smoke a joint or blunt in a dorm room. Always wait 10 mintutes after you smoke with the door closed and fans running so the smoke can clear out. If you're worried that the smell has gotten out in the hallway, call a friend down the hall and ask them to walk by your door and see if they can smell anything. These methods worked for me dozens of times last year. Thankfully I'm moving off campus this year so I won't have to deal with it.