sponge on . sponge on or off {v. phr.} To exploit parasitically; depend upon for support. He is already forty years old, but he refuses to go to work and sponges off his retired parents. Categories: add yours {v. phr.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2024 To section: S Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Post my comment