bell the cat, who will

Who has enough courage to do a dangerous job? For example, Someone has to tell the teacher that her own son started the fire, but who will bell the cat? This expression originated in one of Aesop's fables as retold by William Langland in Piers Ploughman (c. 1377), in which the mice decide to put a bell around the cat's neck as a warning device but then can find none among them who will actually do it.