If you have a brother or sister with a lot of posters in their room, and you want to give them a shock, then this is the perfect prank for you. Simply switch all his/her posters with either embarrassing photos of them, or bands or famous people they dislike, or maybe random stick drawings, that make fun of them. Remember not to do this to someone who doesn't have a very good sense of humor. Or you could do the classic vandalism on them, your choice. Remember to be extremely creative.