When a gay man, after being pounded in the ass, goes to take a shit and is unable to do it. He strugles really hard for a few hours and eventually shits out a premature baby.
"Todd just had a terd baby!"
the spawn resulting from unprotected anal-sex. coined by Adam Corolla on Loveline back in the day.
Q: "can i get my girl pregnant from anal sex"
A: "have you ever heard of a terd baby?"
"Elton John Jr. is a terd baby for sure" - me