Verb. To feff is to touch someone else in a way or manner that makes them feel uncomfortable, whether it be through sexual inappropriateness or violation of personal space.
Don't leave your girlfriend with mr. X over there, he'll feff her
fefs is a faroese word for the word: Fupa which stands for Fat Upper Pussy Area, if we translated it to Faroese it would be: Feitt Erva Fisu Stað. And that's why we say Fefs.
Tú hevur eitt lekkurt Fefs, góða.
( in Eng) that's a hotFupa you have there, sweetie.