Often found to be carpenters, due to a fondness for wood, a backdoor burglar will glady insert his dowel rod in the one place nature never intended - your bucket of an arse. Like any good burglar, if he spots an opportunity he'll be quick to knock in your brown door and paint it white on the way out.
It is important to stress that unlike ass-bandits, marmite-miners, fudge-packers, butt-pirates and the like, generally speaking a backdoor burglar will plunder your ass without your consent/and or knowledge.
However, particularly fiesty homosexuals will mutually burgle each others arses, due to the fear/excitement of being caught - like the old fashioned game in which you must steal the keys without the other noticing. In this case, replace keys with butt-fudge.
Guy 1: "Dude my ass is sore today, what the hell happened at Mike's party last night."
Guy 2: "Dunno man but you were pretty drunk and I noticed some dodgy pervert hanging around, perhaps you got your backdoor burgled?"
Guy 1: Hey man, shall we go into Club X tonight? My uncle says its good fun.
Guy 2: Maaaaate. Are you a fucking ass bandit? That place is for backdoor burglars ONLY.