Arriver comme un cheveu sur la soupe.

Le mot du jour : “arriver comme un cheveu sur la soupe”
“Arriver comme un cheveu sur la soupe” can be translated by : “to arrive or to happen like a hair on the soup.”

It means that someone has turned up at a bad time, or that something is irrelevant.
You could say, for example : “Je me reposais tranquillement quand mon voisin est arrivé comme un cheveu sur la soupe” (I was resting quietly when my neighbour turned up unexpectedly)

Or you could use it this way : “Sa remarque est arrivée comme un cheveu sur la soupe” (Her comment was completely irrelevant)
Either way, a hair in the soup is never good 🙂

Arriver comme un cheveu sur la soupe - Lawless French Idiom