Abbr. often near "R.S.V.P."

• T.G.I.F. party request
• Party invite initials, sometimes
• Letters on some invitations
• Letters of invitation?
• Party letters
• BBQ invite letters
• "We won't be bartending"
• Letters on a party invitation indicating that booze won't be provided by the host
• Party rule, for short

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
initialism (acronym) for "bring your own bottle" or "bring your own booze," by 1951.