A girl who you think has an unattractive face until you finally see her up close and are pleasantly surprised....
"Joe dude I thought that chick was a fuckin ugly cunt, but she actually had a I can't believe it's not butterface."
Thinking a woman has an ugly face based on voice or body only to find she is smokin'.
That new bitch has anIcantbelieveitsnotbutterface.
A girl who is so ugly you can't bare to look at her. But her face is actually not that bad.
Rob "Yo check out that huge b*tch"
Dimitri "Wow shes huge but her face isn't that bad"
Greg "Holy shit she's got an I can't believe its not butter face"