once hell freezes over

Never; at no time. Sure, Bob, you can be the head of this company—once hell freezes over!

See also:

when hell freezes over
see (one) in hell before (doing something)
would see (someone) in hell before (one) would (do something)
be hell
hell on
hell on (someone or something)
hell no
hell of a
hell of a someone/something
a hell of a

All content on this website, including dictionary, thesaurus, literature, geography, and other reference data is for informational purposes only. This information should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional.