I'll eat my hat!

eat (one's) hat

A humorous action that one will allegedly take if something very unlikely happens. Kevin is always late, so if he actually shows up on time, I'll eat my hat.
See also: eat, hat
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

I’ll eat my ˈhat!

(spoken) used to say that you think something is very unlikely to happen: They’re always late — if they get here before eight o’clock, I’ll eat my hat.
See also: eat
Farlex Partner Idioms Dictionary © Farlex 2017
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References in periodicals archive ?
The tournament truly sparked to life in the heavyweight clash between Spain and Portugal, and if there's a finer game in this tournament I'll eat my hat! Cristiano Ronaldo once again proved himself as the best player to have ever graced this planet with a scintillating hat trick, including a late trademark free kick to rescue a point.
''If I can't answer one question I'll eat my hat!'' Kelly bragged.
"I've had guys say to me already, 'If you play until you're 30 I'll eat my hat!' "But look, if I make 30 I will be happy.
"I've had guys say to me already 'if you play until you're 30 I'll eat my hat!' But look, if I make 30 I will be happy.
If they don't win the lot I'll eat my hat! sammykims Massive spending yet nothing in the department that lacks most, defence.
"Manchester United are nowhere near the top and if the season finishes like that I'll eat my hat!" said Davies.
If he wins I'll eat my hat! (Ed: We'll look forward to that then...).
DCC put on a show second to none and if we don't see the Australians there before long I'll eat my hat!