To literally be hit in the face with your own boobs (possibly while running).
Can be used to describe most situations
"I heard you drank a lot last night dude"
"Ah man I was so bapfucked, god knows what happened..."
"Yo homie check out that honey's swag over there..."
"Woah she's hot, I'd let her bapfuck me anyday"
"Ah girl, the other day I wasn't wearing my sports bra...got totally bapfucked on the treadmill."