I used to have a mannequin in college (store across the street from my dorm was just going to throw him away! What else was I supposed to do?). Anyway, my friend across the hall would frequently come home drunk and I knew his door was always open. One night I brought the mannequin in, placed him near the front door and turned off the lights. When my friend came stumbling home around 2 a.m., I was able to hear the scream from across the hall.
EDIT: Here's a pretty good video with a few more ideas http://Post original url/SeeWhatIDidThere