chestnut

To do a difficult, and often dangerous, task for someone else's benefit. David really pulled my chestnuts out of the fire that time he saved me from drowning. I can't believe my car broke down on this desolate road late at night—thank you so much for pulling my chestnuts out of the fire and picking me up!

A topic, saying, or joke that has been repeated so much that it has become boring or irksome. Whether there's truth in it or not, I can't stand that old chestnut "follow your heart."

a subject, idea, or joke which has been discussed or repeated so many times that it is not interesting or funny any more I wondered whether there might, after all, be some truth in the old chestnut that one's school days are the happiest of one's life. Play allows us to rediscover the child in ourselves - that old chestnut.

A stale joke, story, or saying, as in Dad keeps on telling that old chestnut about how many psychiatrists it takes to change a light bulb . This expression comes from William Dimond's play, The Broken Sword (1816), in which one character keeps repeating the same stories, one of them about a cork tree, and is interrupted each time by another character who says "Chestnut, you mean . . . I have heard you tell the joke twenty-seven times and I am sure it was a chestnut."