Undeniably one of the sneakiest and scariest ASSassins of the world. Known for being able to PENETRATE the most secure facilities in the world with incredible ease with the sole intention of raping man ass. Butt ninjas have super human abilities allowing them to walk through walls, turn invisible, cling to ceilings, and run faster than light... translation: they will have sex with your butt no matter what.
Bro-1: "I was too afraid to shower at the empty gym last night. I kept thinking I saw a butt ninja out of the corner of my eye."
Bro-2: "That's a lie, a butt ninja would've never gotten spotted by a douche like you. Probably just a normal rapist."