a person who without prior knowledge or consent, sticks anything in or around the premises of your butthole.
see also: Buttfinger, Asshole Assassin,
After my best friend Andrea did the weekly walk of shame from the guys house last night all the way back to my place, she then told me how her Thursday night fuck buddy "accidently" put a finger in her butthole.
Andrea: At first I thought he just got it in the wrong hole, but then it happened AGAIN...
Liz: Yo he totally violated your ass on purpose. He's a secret butthole bandit!