faafetai
Faafetai is a word from Samoa that means 'thank you' but sounds like you're saying 'f*** you' in a fancy way.
My teacher said 'faafetai' when I failed the test but she gave me an A anyway.
My friend said 'faafetai' when I took his last pizza slice.
My dad said 'faafetai' after I ruined his favorite shirt.