You’re still hanging a sock on your doorknob to let your roommate know you’re hooking up? That’s so 1997. Welcome to the future where custom QR codes can alert them to come back in an hour while also giving them a moment of entertainment. Leave it to horny college dudes to figure out how to turn technology into a way to brag about sex. By the way, if you’re wondering what the QR code links to, it’s this glorious gif that instantly turns Harry Potter into your wingman. Godspeed Harry, godspeed.