I will eat my hat

“I will eat my hat”

I will be very surprised; used to express how absolutely, positively certain a person is about something.
من اسمم را عوض می‌کنم. (عامیانه)، زمانی فرد بکار می‌برد که کاملا از چیزی مطمئن باشد.
Example 1: If she actually marries him I’ll eat my hat.
Example 2: If we can’t beat a second-rate team like Sheffield, I’ll eat my hat.
Example 3: She’s always late. If she gets that train I’ll eat my hat.