*Comme on fait son lit, on se couche = As you make your bed, so you must lie on it.
Se coucher comme les poules = To go to bed with the sun, very early.
Coucher sur la dure = To lie on the ground, on the floor.
Coude
Il ne se mouche pas du coude (fam.) = 1. He is no fool. 2. He does things in grand style. (See [Pied].)
Il a mal au coude (fam.) = He is very lazy. (See [Main].)
Coudée
Avoir les coudées franches = (lit.) To have elbow-room; (fig.) To have full scope.
Coudre
On ne sait quelle pièce y coudre = One does not know how to prevent (or, cure) it.