Les 400 coups

(un) coup = a knock / a blow. Pronounced koo.

Lots of expressions with coup:
un coup fourré = a dirty trick
un coup bas = a blow below the belt
faire les 400 coups = to raise hell. Also the name of a famous French movie by François Truffaut.
un coup de barre = a sudden fatigue (like being hit with a bar)

E.g.
J'ai un énorme coup de barre = I'm suddenly extremely tired
Il m'a fait un coup de pute = he screwed me

Pute (hooker) is a word I'll have to cover some day.