When you fall asleep at a party/gathering and a bunch of your mates run in naked and jump on you shouting "sex police!!" in a extreamly high pitched, camp German accent.
Almost always happens when there is no girls at the party/gathering.
Rams: "Haha, aye alright."
*2 minutes later...
Rams and Potter: "Sex Police!!!!!!" (Jump on Ewan)
Ewan: "Arrrgh! Aw naww!"