What's A Truncheon?

Two gay men decide to get themselves chased by the police for a laugh. So one of them offers to beef a copper, and promptly they are chased by two burly policemen, who are very pissed off. Soon they arrive at a two way junction. They decide to split up, so one runs to the right and escapes, and the other one ends up in an alleyway with a dead end. Fearing a shit kicking, he jumps into a bin, and pulls the lid over his head. 2 minutes later the police run in and one of them pulls out his truncheon.
"Right, ya poofy wee bastard! If I find you I'm gonny ram this truncheon right up yer arse!"
"I'm in here!!!"