manger son chapeau bedeutet auf Englisch

eat humble pie▼(to admit one's faults)
verb
[UK: iːt ˈhʌm.bl̩ paɪ] [US: ˈiːt ˈhʌm.bl̩ ˈpaɪ]

eat one's hat▼(to express disbelief about a proposition)
verb