Sex Alert Announces When You're Having Sex, Which is NeverSEverybody had a method in college to warn their roommates to stay the hell away when you were lucky enough to con someone into coming home with you. Be it a sock on the doorknob, shoes outside the door or a gigantic X on your whiteboard, it had to be clear enough to get the message across without looking sleazy to your new friend. This Sex Alarm doesn't aim for such subtlety. You hang it on your doorknob, and if anyone approaches it yells out that someone is having sex inside. Which you then won't be, you creep. Way to screw it up in the home stretch. [Product Page via Nerd Approved]