stand up with . stand up with {v.}, {informal} To be best man or maid of honor at a wedding. A groom often chooses his brother to stand up with him. Categories: add yours {informal} {v.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2025 To section: S Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Post my comment