Il se mettrait en quatre pour un ami = He would go through fire and water for a friend.
Faire le diable à quatre = To kick up a terrible noise; To exert oneself to the utmost.
[This expression originated in the time of the miracle plays, when four performers represented la grande diablerie, and less than four la petite diablerie.]
Entre quatre-z-yeux (fam.) = Between ourselves.
On le tenait à quatre = It needed four men to hold him down.
Il se tenait à quatre pour ne pas lui dire des injures = It was as much as he could do not to abuse him.
Travailler comme quatre = To work like a nigger.
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