There was this super randy guy in my dorm (coed) who was always shagging anything that walked. I enlisted the RA to let me in his room &

tied very thin, nearly invisible fishing line to the the springs under his mattress and strung it out the window, tossing it to a friend

waiting in the big tree in the center of the courtyard where he tied it to a cowbell. So when he got busy, the cowbell rang in the courtyard

LOL that's awesome