We often say, 'He/she sings like a cat on a hot tin roof' or 'he/she is wailing like a banshee'.

Western music have eight tones or music notes, two of them are 1/2 tone, so it is seven tones with eight music notes. But, in Chinese, it is five tones and five music notes. When the music notes is not in the complete set, it is not able to compose any musics. It is obvious when it is referring to a person, it means that he/she doesn't have the talent or capability to do anything.

Right Bean, and then if they sing anyway, it's common to say, "Don't quit your day job". It's a friendly way to chide somone, and it means that they don't sing well enough to get paid for singing. But I think the chinese way to say it (harmonically-challenged) is pretty funny, and I might use it myself.

cant carry a tune ex:Give me a break! She cant even carry a tune..! AND another saying i guess is " tone-deaf".... you could say someone is a tone-deaf.. cant sing well!