B.Y.O.B. is an initialism for "bring your own bottle", "bring your own beer" or "bring your own booze," first recorded in the 1950s. It is usually used to indicate that the host of a party or social gathering will not be providing alcoholic beverages, but that guests are welcome to bring their own if they choose to do so. Also used as a politically more correct phrase "bring your own beverage".

BYOB, one of the more recent additions to the Something Awful Forums, is a off-topic forum where members can "chill out".

4-letter acronyms

BYOB