What does it mean to eat your hat? Does it mean to really eat the hat or does it mean you have disagreement to someone?
This expression appeared in the comments of Shawn Mooney's answer to Can we add “more” with an adjective to convert it into comparative degree?:
@kiamlaluno, I want to make peace with you, but maybe this particular post is not the place to do so. I fail to see how your suppositions about what OP might have intended negate my response. However, you and I have butted heads before when it was after midnight my time and afterwards I had to eat my hat, so please clarify. As far as my foggy mind can comprehend, the previous, linked post, together with my answer to this post, sufficiently answers OP's queries; on the other hand, your follow-ups seem but red herrings. I have eaten my hat on stack-exchange before, so…give me more. – Shawn Mooney 4 hours ago
I have never eaten anybody's hat, nor have I eaten @nohat's hat. You open your answer saying that this question is not a duplicate, but what you are supposing asked from the OP is not what the OP is asking. It seems the OP is (wrongly) using comparative for words like taller, and not more beautiful; when he says beautiful doesn't have the comparative, he means beautifuller is not an English word. Then, he is not asking about more taller, but more tall, for which there is already a question, even if that is about bigger. – kiamlaluno 4 hours ago
Best Answer
It is a "display of confidence", meaning "submit myself to something unpleasant if I prove to be wrong" as in:
To say "afterwards I had to eat my hat" is to admit that you were wrong.
http://www.phrases.org.uk/meanings/eat-my-hat.html