An acronym for Bareback Full Service. A term generally used within online escort/prostitution communities to refer to unprotected (condomless) vaginal sex with a prostitute. The term also encompasses unprotected anal sex, and is sometimes used to describe non-prostitute (civilian) sexual encounters as well. Considered the holy grail by some Johns(customers), and frowned upon (at least publicy) by others. Most mongers (another word for John) are guilty of bbfs at least several times in their lives.
In the heat of the moment, I jammed my dick in the prostitutebareback without a condom and came in her pussy. After the bbfs, I got tested, and luckily I came out negative for STDs.