Also known as "SBB", a stupid bitch baby is who that person was in the past except that person has to be a stupid ass child who was an annoying little shit. It's a good way to separate who you are now from who you were as a way to cope with your own past actions.
Dale: what would it be like if you met your own stupid bitch baby?
Eli: they'd probably be confused and say "whaaat?? There's only two genders! What do you mean 'non binary'?"
Dale: oof. That sucks
Eli: what about yours?
Dale: my SBB would probably be asking how the fuck I'm this constantly horny
Eli: jeez