UFF stands for
Ugly Fuck Face
People usually say this when a really bitchy girl is trying to hit on them and give them some type of STD. The girl usually has a rusty cunt. When doing the girl she usually screams. She will also occasionally squirt causing a mess. Then you have to scream YOU FUCKING UFF.
That UFF over there is trying to seduce that poor nerd, I guess we should warn him about the STD's that she has.