12. Silence is golden
Sometimes it is not possible to play a roommate joke because there is pent-up aggression or a general sense of dissatisfaction. Sometimes there is a specific incident or bad habit that just needs to be corrected. As the old saying goes, you sometimes have to burn to find out that the pan is hot.
From this list we can conclude that the roommate at the receiving end of this prank had a bad habit of forcibly opening the door as she entered the room, so she entered the closet behind. Whoever that unhappy soul was, they were about to get a rough awakening as that grip slammed into the air horn.