Mandarin xie1-hou4-yu3, "a saying (that only makes sense) after a pause".
A kind of two-part Chinese idiomatic expression that depends on a pun or a leap of association to understand. Homophonous morphemes are extremely common in Chinese, especially in northern varieties such as Mandarin, and northern Chinese people make fruitful use of puns in xiehouyu to conceal trenchant comments.
The first part of the xiehouyu is an innocuous-sounding line in colloquial language. This line suggests the second part, a word or short idiomatic phrase, often somewhat literary in flavor. However, the suggested phrase is usually well-known expression that may have considerable caustic force. It is customary for the person desiring to make the comment to pause after the first part, to give the hearer a moment to get the point and supply the "punchline". The punchline is not infrequently a double entendre. If the punchline is harsh enough, it may simply be omitted by both speakers, who understand what is meant by the opener alone.
A few colorful examples follow, from my own notes of Beijing dialect. Many of those xiehouyu found in reference books I have seen are rather dull and do not even involve puns.
- Opener: Ji1dan4 li3 tiao1 gu2-tou. ("To try to pick out bones in a chicken egg")
Punchline: mei2-char2 zhao3-char2 ("to find fault where there is none")
- Opener: Da4 gu1-niang qiao2 liao2-zi ("spinster seeing a penis")
Punchline: ren4-he2 ji1-ba shi4 ye3 bu4-dong3 ("doesn't know a fucking thing")
- Opener: yao2-jier3 chuan1 qun2-zi ("prostitute wearing pants")
Punchline: mao4-chong1 hao3-ren2 ("pretending to be a good person")
- Opener: hua1 hu4-be-la3 ("multicolored shrike")
Punchline: ge2-se4 ("having a color of one's own", i.e., quite distinctive)
- Opener: jier4-mao2 ("shuttlecock feathers")
Punchline: zhan4-zai4 qian2-yan3-shang4 ("stands on the hole in the coin" i.e., is only interested in money)
Here are a couple of good ones from a 1984 Chinese dictionary:
- Opener: Chi1 zhu2-gan1, e1 zhao4-li ("eat a bamboo pole, shit a bamboo strainer")
Punchline: bian1 ("to weave" i.e., to make things up)
- Opener: Cang1-ying2 fei1-jin4 niu2 yan3 li ("fly flies into an ox's eye")
Punchline: zhao3 lei4 chi1 ("looking for tears to eat" i.e., looking for extra work - "tears" and "tiredness" are homophones)
- Opener: ji1 bu4 sa1-niao4 ("the chicken doesn't piss")
Punchline: zi4-ran2 you3 yi2-bian4 ("there will naturally be a pissing" i.e., there will naturally be some convenient way - "pissing" and "convenience" are homophones)
Thanks to Cletus the Foetus for a better choice of diction in one of these.