Standing for "Unidentified Party Bruise".
the common (but not remembered) cause for this is :
a) running into things
b) falling on your face c) general clumsiness
These contusions are noticed most likely the morning after, with a slightly hungover expression of "huh?"
"Sh**, I totally don't remember getting this U.P.B"
"I thought you punched me in the face, but now I find out I just fell over"
2. A beat-up, turned-out vagina that is usually accompained by a foul odor and/or taste.
You're gettin' it on with a chick that you've never been with before. You go down to drink from her natural spring of goodness only to notice that she has one of those vaginas that looks like someone reached up in there, pulled it inside out, and left it hanging. "Damn... that bitch has got U.B.P.L.'s!!!"