hard-on . hard-on {n.}, {vulgar}, {avoidable}. An erection of the male sexual organ. Categories: add yours add yours {avoidable} {n.} {vulgar} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2025 To section: H Subscribe to: American Idioms► Also consider the parent subscriptions (3)Idioms feedEnglish languageHome page and general feed Post my comment Post my comment