B.Y.O. . B.Y.O. (Abbreviation) {informal} Bring Your Own. Said of a kind of party where the host or hostess does not provide the drinks or food but people bring their own. Categories: add yours abbreviation {informal} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2025 To section: B Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Comment on this entry