When a guy injects his penis into the anal opening and has sex with it for a long period of time, well the shit noodle is what comes from the tiny little whole in this penis the next morning. It's literally a noodle of shit.
Poop- "HOLY SHIT MAN, HOLY SHIT, I CAN'T FIT IN THAT LITTLE HOLE DUDE, I CAN'T FIT."
Man- "GET OUT POOP, GET OUT. YOU'RE HURTING MY SHAFT."
Poop- "I GOT IT. SHIT NOODLE FORM. I'M NOODLIN' OUT."