this is a term Hispanic people use to describe the specific point in time when a super formerly hot chick goes to being not hot.....this typically occurs to former hot chicks around menopause, or when they decide to one day, cut off all their hair, get fat, and wear glasses instead of contacts.
"Damn, have you seen so-and-so lately....?"
"no, why, is she even more hot than the last time I saw her?"
"Hell no! she hit the viejaso! seriously dude, I thought it was her mom when I ran into her at the liquor store..."