When a woman is impregnated while participating in anal intercourse... Details are left to the imagination.
Bro 1: Dude, you know that girl Rachel?
Bro 2: Yeah man, I heard she got knocked up!
Bro 1: Yeah, and she said that I'm the father, but I just Butt-fucked her, since she had a nasty Kraken Snatch
Bro 2: you must have pulled a rusty bayonette!
Inserting an erect penis into someone's anus, and then pushing it back and forth between two large breasts to simulate a stabbing motion.
"So I found out she liked anal last night. When she wasn't paying attention i flipped her around real quick and gave her a real good rusty bayonette.