I once stayed in a hostel and I was on the bottom bunk, I thought the bunk above me was empty but the guy came in real late after I'd gone to bed but wasnt asleep, anyway, it was this old metal and wire bunk and after about ten minutes I here this 'erk, erk, erk, erk' sound and the whole bed starts rocking as the guy above decides to knock one out, so not knowing what to do I just punched the bottom of the mattress above, and he stopped immediately. So I fell asleep, and what I guess was about three hours later got awakened again to 'erk, erk, erk, erk'..... this time I just decided to let him get on with it and he didnt last long. By the time I woke up the next morning, he was gone, and asking around no-one else in the room remembered ever seeing him....