2) While doing a girl from behind, the guy pulls out and nuts on the girl’s back. The jizz is then collected in the dimples of the girl’s lower back.
3) Indentations on a girl's lower back that can be used as thumb grips during doggy style prior to becoming filled with semen.
Synonyms: 1) Dimples of Venus; 2) Sacral dimples; 3) or simply, back dimples.
"Ughhh... yeah, do me doggy style baby, and before you cum, I want you to pull out and fill up my cum reservoirs with your hot load!"
"Hey, wasn’t that scene in "Kick-Ass" awesome when Kick-Ass was rubbing lotion his friend’s back, and the camera panned down for a perfect close-up of her cum reservoirs?!?"