When the huge boobs of a mom figure are squeezed into your chest when given a long enthusiastic hug. Typical offenders are grandmothers, aunts, and other older female relatives. Usually brings on feelings of utter nastiness.
John: Honey, what's wrong with you?
Jane: Omigod John, I just got the mom boobs from your mom!!!
great boobs on a woman aged enough to look like shes had kids already, commonly seen at concerts, rodeos, parties, bars, nude beaches and most other places involving alcohol consumption
"Dude, look over there, mom boobs, ten o clock!"
"no man, im checkin out the mom boobs right behind us, that mom is hot as hell."
O shit man, those are damn nice mom boobs, but the nipples are kinda different sized"
"yea cuz her kid like to suck on the left one more."