être têtu comme un âne

To be extremely stubborn

This expression describes someone who is particularly obstinate or hard to convince, referring to the donkey's reputation for being unwilling to move when it doesn't want to.

Mon fils est têtu comme un âne, impossible de lui faire changer d'avis !

My son is stubborn as a mule, impossible to make him change his mind!

First recorded in 1700. Donkeys have been seen as stubborn since Sumerian times, but their reluctance to move is actually a survival instinct from desert life.