Passer à la casserole

Literally: To go into the saucepan

Example: “Pendant le contrôle fiscal, toute sa comptabilité est passée à la casserole.” — During the tax audit, all his accounts were put through the wringer.

Origin: Early 20th century, and it has shed senses since — it once also covered a harsh purgative, and the old treatment for venereal disease in which mercury was heated in a pan so the patient could breathe the fumes. The core is the verb: since Molière, y passer means either to suffer something or simply to die, and poultry is killed before it goes anywhere near a pan, so the cooking vessel reads as the end of the line. French slang kept the suffering and dropped the cooking — a crook caught in the act is as cuit (cooked, meaning done for) as the missionary in the cannibal's pot. The third sense arrives by a cruder route: a pan is what you sauter (sauté, but in slang also to have sex with) things in.