Next time, sneak in when they are out. Take the glass dome off the overhead light and remove one of the bulbs (has to be old style incandescent). With a glass cutter, carefully cut the glass bulb from the base being careful to not damage the filament. Wipe the glass bulb down to remove your finger prints before you discard it in a trash can on another floor and put the remainder of the bulb back in the socket. Now attach an M-80 fire cracker to the filament. Crap in a baggie. Now stick the fire cracker into the baggie and tape it to the ceiling. (you did turn off the light before all of this didn't you, if not, sorry).
Wipe down the room, vacuum for hair and other fibers, run a hepafilter air cleaner for a couple of hours to remove all your DNA, then sit back and wait for them to come back and turn on the light.
Easy and fun.