Green’s Dictionary of Slang

B.F.F. n.

(teen) best friends forever; also attrib.

Urban Dict. 1 Nov. 🌐 BFF Acronym - Best Friends Forever KKIT!!! stay cool and don't skip school!! sincerely, Britney. PS: BFF!
[US]Ruderman & Laker Busted 124: ‘Wow, Barbara has a new BFF’.
[Aus]G. Gilmore Class Act [ebook] Davie was always a sucker for the BFF act.
www.verywellfamily.com/a-teen-slang-dictionary 10 Mar. 🌐 BFF - Best friends forever.
[UK]J. Meades Empty Wigs (t/s) 819: [W]e had been a team now it was just Part-Time Tabitha and me... me and my BFF.