Reading via mastodon translate a thread by a French poster about recent actions by Macron and partway through got slapped in the face with the discovery that "I'll eat my hat" is an idiom in France as well as America ("Bon, je mange mon chapeau, et c'est pas très bon.")
Is this… how universal is this? Do they eat hats in Germany? Russia? What percentage of earth has a local-language idiom for eating hats?

Census from responses:

Eat hats: English, French, Norwegian, Swedish, Danish*, Icelandic, Hungarian, Finnish, Estonian*, Hebrew

Do not eat hats: German, Russian, Spanish, Italian, Polish, Yiddish, Mandarin Chinese

Contradictory data re: hat-eating: Dutch

* Hat may optionally be "old"

Provisional unified theory of hat-eating (highlighted countries eat hats to express an unlikely event has occured)

The major outstanding question here is whether they eat hats in Estonia*. Is this a universal feature of Uralic languages

* Update: YES

@mcc Spaniards don't eat our hats, and I'm struggling to think of an equivalent saying.
@ehproque My knowledge of Spanish is limited but I don't think I've ever heard an analogous idiom from ES-419 either