bffl Share definition Flag Abbreviation for either:1. "Best Friends For Life." Usually used by pre-teen girls.2. "Bitch, Fuck your Face, Loser!" 1. Kylie: heyyyyySara: oh my gosh did u see hannah hanging out with caroline?Kylie: yeah, i head they're, like, bffls now!Sarah: OMG!!2. Catherine: oh my gosh i broke my nail!!!!!! the world is going to end!!!!!!!Random guy: BFFL!!!!! bffl by JDUGSMAC September 18, 2010