se serrer les coudes

to support each other closely

Used for people banding together and backing each other up when times get tough, whether that's a family, a team or a whole industry.

Face à la crise, les commerçants du quartier se serrent les coudes.

Faced with the crisis, the shopkeepers in the area are backing each other up.

Origin uncertain. It's often guessed that the image comes from people standing shoulder to shoulder with elbows touching to form a united line, but nobody pins down exactly when or where the phrase started.