last year i was a ski-instructor on a skicamp, we had like 150 kids so we also had a staff of like 20 ski/snowboard-instructors, long story short, the last night of such a camp is always a party night and all the instructors come party.
this year we had 2 hottie ski instructors who went to sleep at like 23h, we couldn't accept this so we(myself and 2 friends in a semi-drunk state) went over there to annoy them and convince them to come party, anyways they were set on going to bed and told us to fuck off and go to our own room. I dunno why i said it, but i told them that our roommate (whos a bit of a geek) already went to bed, took the key and locked us out. (which was a total lie, i had the key in my pocket)
Anyways, it didn't quite catch on, so they still told us to go away and if we really couldn't get in our room they jokingly suggested that we should crawl over the balcony (sleeping rooms of the kids were bordering our own room so we could easily go through one of their rooms, go to their balcony and enter our room (second floor)
So we finally left the room when suddenly i had a spark of genius !
I told my friends that i'd pretend to have fallen off the balcony while attempting to get in our room and that they should rush to the girls to ask for help. I walk down the stairs, take a pack of ketchup from the luncharea, i take a mangled position underneath the balcony and squirt some ketchup onto my head and on the asphalt beneath. i give a thumbs up to my friends and they rush in a faked 'panic' to the girls chamber, they look out of their own window to check and see my mangled body 3 floors below them, they both hop into their shoes, with cellphone and first aid kit ready they rush down, one of them didn't even put on cloths, just a bathrobe :P
they arrive at my body and start calling me out and gently shaking me to check for a response, i keep playing 'dead'
right as they both are sitting right next to me and one of them is getting ready to call 911 i jerk up and scare the living hell out of em, one ran away and the other one slapped me in the face :P
Luckily they had forgiven us by the next morning :P
it's amazing how well that prank worked considering how drunk we were :)