The saying "I'll eat my hat" conjures up such a funny image in our minds that people have continued to use this antiquated idiom every time they're confident something will not happen.
But this idiom can't possibly originate from someone actually eating their hat, can it?
Karl Smallwood of Today I Found Out dug around for an answer and came up with an entry from Homer Travestie by Thomas Bridges, dated 1762, which contains the saying:
For though we tumble down the wall, And fire their rotten boats and all, I'll eat my hat, If Jove don't drop us, Or play some queer rogue's trick to stop us.
Karl then goes on to explain that Bridges merely streamlined the "now defunct utterance “I’ll eat Old Rowley’s hat” that had essentially the same meaning", Old Rowley being a nickname used to ridicule King Charles II.
Charles II was known for wearing foppish hats, so this is likely why the saying deals with eating a hat rather than some other garment.
So has anyone actually eaten a hat after saying the phrase?
An Atlanta Falcons fan did after he claimed they wouldn't lose to the Carolina Panthers in 2015 or he'd "eat his hat"- he ate it along with a Wendy's chicken sandwich.