"FOFF!" is also the sound you emit when they try to befriend you.
Got an "Add Me" request from Lauren, but she can just FOFF.
thats all it means its plain and simple and used when your words are censored like in online chatrooms and gaming and in public places like school.
the "bad" words are replaced or omitted so you can get you point across when someone pisses you off.
Person 1 "your ugy"
Person 2 " f off"