stands for Blowjob From Friend and usually used by people who's so close and sending weird texts like "ILY" which means I Lick Youngsters. Beware of these predators because they could even seduce you to be their next target.
*two peoplechatting to each other*
one person: bro i got a BFF!
other person: ayo you are very lucky!! i need a BFF too.
a lie. there is no such thing as having a BFF because eventually you will just stab each other in the back one too many times and it will be over forever.