Chanter comme une casserole

Literally: To sing like a syringe / like a saucepan

Example: “Mon oncle adore le karaoké, mais il chante comme une casserole.” — My uncle loves karaoke, but he can't carry a tune in a bucket.

English equivalent: Can't carry a tune in a bucket

Origin: From the start of the 19th century, and no lexicographer has produced a probable explanation. Walter Gottschalk notes only the sound of seringue against sirène and serin — you meant to sing like a canary and came out a siren — which would make the syringe a joke slid in on the resemblance. There may also be a link to the old slang sense of seringue for a thoroughly stupid person, on the reasoning that an idiot could hardly be expected to sing in tune. And seringue does come from Greek syrinx, meaning a tube but also a shepherd's pipe, which leaves room for a sound judged according to the shepherd. The saucepan needs no defense: it is the sound of the pans traditionally tied behind a wedding car.