BBS
The acronym "BBS" (or "bbs") stands for "baby's bottom smooth." It refers to a shave that leaves the skin of the face "as smooth as a baby's bottom." This shave is considered the best possible shave. Although a shave might technically be quite smooth but also irritate or cut the face, a "BBS" shave implies not only superlative smoothness but also comfort.
A related set of three-character acronyms is "WTG," "XTG," and "ATG" ("with the grain," "across the grain," and "against the grain," respectively). Shavers will combine more then one kind of "pass" in order to accomplish a BBS.
Other acronyms frequently used at SRP can be found on the page Acronyms_and_Abbreviations.