To acquire ownership of something, usually incarnate, by forcefully pushing said object into ones vagina (or anus) then subsequently pushing it out in an act of "birth." This is commonly done, but not limited to, aesthetically pleasing children that you wish to make yours.
"Oh Alex!!" Laura said with utmost excitement, "Isn't baby Benji larsman S00 cute! I will make him my own flesh and blood by reverse birthing him!"
3π 12π
(adj) Having a shaft and meatus so thick, insertion into a vagina (or similar orifice) is akin to childbirth, but in reverse.
Last night at the bar, I met a guy named Tyresius. Drinks and conversation flowed. One thing led to another and before I could say clitoris, I was being ripped by Tyresius' reverse birth girth. Ooo-la-la. Ouch.
4π 3π
When a bald man inserts his head into a womanβs vagina.
If you think that fisting porn is gross, you should see this reverse-birthing video.