that'll be the frosty Friday
Synonym of that'll be the day (“said in reply to something that one believes will never happen”).
Meaning adapted from Wiktionary, available under CC BY-SA 4.0.
“You think he will pay you back? That'll be the frosty Friday.”
“He plans to wake up at five for a run? That'll be the frosty Friday.”
“You expect a free meal from that cheap restaurant? That'll be the frosty Friday.”
“My brother promised to clean the entire garage by noon, but that'll be the frosty Friday.”
“She says she will stop checking her work emails during our vacation, but knowing her, that'll be the frosty Friday.”
“The landlord promised to fix the leaky roof by tomorrow morning, though we all know that'll be the frosty Friday.”
“When the politician claimed he would lower taxes without cutting any public services, the skeptical voters knew that'll be the frosty Friday.”
disputed origin
The expression is probably a humorous elaboration of the phrase *that’ll be the day*, with the alliteration of *frosty* and *Friday* chosen for phonetic effect. It is also thought to evoke the image of a cold day in Hell, referencing the proverbial time when Hell finally freezes over.
Last updated August 10, 2026