chefying said he'd cover this topic, but it seems he's gone AWOL for the moment. so, i'll give it a go and hope he jumps in and carries on!
Chinese Idioms 成語you encounter them everywhere, these (predominantly) four-word sayings. people often use them in everyday conversation without even realizing it. and others, attempting to be snottily sagacious, will try and teach you about life, the universe, and everything by stuffing them down your throat. and it's a bit of an idiosyncrasy and irony that these sayings are most often in four-word format, since there's such a taboo surrounding the number four.
anyway, below are some of the ones i like best, are the most popular, and/or are simply ones you really should know if you want to be "in" with the chinese.
(and yes, some you'll encounter in wuxia novels and adaptations.) i won't even pretend to be giving a representative sample of them, since there are upwards of 20,000, by some counts. and you'll occasionally notice some that are eerily similar across cultures (i.e., english). i'll be grouping them by the first character/word, just to have some sort of categorization--most don't have anything else in common.
1. 一 (yí)the ones beginning with "one" are generally the most popular and numerous
一無所有 yī wú suǒyǒu (one not have)
meaning: to have/own nothing
English equivalent: to not have a penny to one's name
一無是處 yī wú shì chù (one lack being place)
meaning: good-for-nothing
一見鍾情 yī jiàn zhōngqíng (one look madly in love)
meaning/English equivalent: love at first sight
一竅不通 yī qiào bù tōng (one opening not linked)
meaning: to be completely ignorant about something; incoherent, not making sense
English equivalent: "It's all Greek to me!"
一舉兩得 yī jǔ liǎng dé (one action, two gains)
meaning: to doubly gain with one action
English equivalent: killing two birds with one stone
一模一樣 yī mó yī yàng (one pattern, one shape)
meaning: identical
English equivalent: spit and image (or "spitting image" as it's usually mistakenly known as)
一舉一動 yī jǔ yī dòng (one lift, one move)
meaning: one's every move
一心一意 yī xīn yī yì (one heart, one thought)
meaning: wholeheartedly; intently
一成不變 yīchéng bù biàn (one tenth not change)
meaning: immutable, unchangeable
一刀兩斷 yī dāo liǎng duàn (one knife, two halves)
meaning: to sever ties; to make a clean break from someone(s)/something
一知半解 yī zhī bàn jiě (one know, half understand)
meaning: partial understanding (of)
一網打盡 yì wǎng dǎ jìn (one net beat completely)
meaning: to eliminate something with one stroke; clean sweep
English equivalent: in one fell swoop
一清二楚 yī qīng èr chǔ (one clear, two distinct)
meaning: to be very clear about, crystal clear
English equivalent: as plain as the nose in your face; beyond the shadow of a doubt
2. 不 bù不可思議 bù kě sīyì (cannot conceive)
meaning: inconceivable, unbelievable
不見不散 bù jiàn bù sàn (not see, not leave)
meaning: to wait until you arrive
English equivalent: be there or be square
不自量力 bù zì liàng lì (not self weigh strength)
meaning: foolishly over-confident, conceited, out of one's depth
English equivalent: biting off more that you can chew
不瞅不睬 bù chǒu bù cǎi (no see, no notice)
meaning: to ignore completely
不分勝負 bù fēn shèng fù (not divide win lose)
meaning: a draw (in a fight/match); a tie; evenly matched
不留餘地 bù liú yúdì (not leave extra ground)
meaning: to leave no room for; make no allowance for; no leeway
不擇手段 bù zé shǒuduàn (not choose method)
meaning: ruthless, unscrupulous
English equivalent: the ends justify the means; by fair means or foul; by hook or by crook
不知不覺 bù zhī bù jué (not know, not sense)
meaning: unwittingly, unconsciously, without realizing
3. 自 zì自相矛盾 zì xiāng máo dùn (self mutual spear shield)
meaning: to contradict oneself, to speak in contradictions; paradox
story:
blog.eteacherchinese.com/learn-chinese/chinese-idiom-ones-spear-contradicts-hisher-own-shield/自相殘殺 zì xiāng cánshā (self mutual destroy)
meaning: mutual destruction
English equivalent: dog eat dog
自由自在 zìyóu zìzài (freedom, lacking restrictions)
meaning: to be carefree/relaxed
English equivalent: to not have a care in the world; to be footloose and fancy-free
自作自受 zì zuò zì shòu (one makes, one bears)
meaning/English equivalent: to reap what one sows; you've made the bed, now lie in it
4. 得 dé得過且過 dé guò qiě guò (can pass, will pass)
meaning: without discipline or planning; mediocre/perfunctory performance
得不償失 dé bù cháng shī
meaning: the losses outweigh the gains
得寸進尺 dé cùn jìn chǐ (have inch, advance foot)
meaning: to be taken advantage of
English equivalent: give an inch and they walk all over you
5. 半 bàn半途而廢 bàntú ér fèi (half-way yet wasted)
meaning: to give up part way
半斤八两 bàn jīn bā liǎng (half catty, eight taels)
meaning: equal measures, no alternatives
English equivalent: six of one, half a dozen of the other
6. sayings in the 言 yán (word) category言而無信 yán ér wú xìn (word yet no truth)
meaning: to say something without meaning it, to go back on one's word, untrustworthy
談何容易 tán hé róngyì (speak what easily)
meaning: by no means easy, difficult
English equivalent: easier said than done
調虎離山 diào hǔ lí shān (move tiger (to) leave mountain)
meaning: to lure an enemy from his home territory in order to attack
7. sayings in the 心 xīn (heart, emotions) category心服口服 xīn fú kǒu fú (heart convinced, mouth convinced)
meaning: to be won over completely
心不在焉 xīn bù zài yān (heart not present thereupon)
meaning: absent-minded, inattentive; preoccupied; woolgathering
English equivalent: be out to lunch; one's mind not in it
心甘情願 xīn gān qíng yuàn (heart sweet, feelings willing)
meaning: to be completely willing; with all one's heart
心灰意冷 xīn huī yì lěng (heart ash, thought cold)
meaning: in despair, disheartened, discouraged
心滿意足 xīn mǎn yì zú (heart full, thought satisfied)
meaning: to be satisfied; perfectly content; gratified
心平氣静 xīn píng qì jìng (heart and breath peaceful) (ALSO 心平氣和 xīn píng qì hé)
meaning: calm
心血來潮 xīn xuè láicháo (heart blood high tide)
meaning: sudden inspiration; spur of the moment; on a whim
English equivalent: lightbulb moment
恩将仇报 ēn jiāng choú baò (kindness will vengeance repay)
meaning: repaying kindness with hostility
English equivalent: biting the hand that feeds you
忘恩負義 wàng ēn fù yì (forget kindness, lose justice)
meaning: to be ungrateful
8. sayings in the 水 shuǐ (water) category水落石出 shuǐ luò shí chū (water sinks, rocks appear)
meaning: to get to the bottom of things; things coming to light
落井下石 luò jǐng xià shí (fall into well, thrown down stones)
meaning/English equivalent: to kick someone when he's down
津津有味 jīnjīn yǒu wèi (saliva with flavour)
meaning: with great relish (especially regarding eating)
9. sayings in the 大 dà (big) category大驚小怪 dà jīng xiǎo guài (big fright, little strange)
meaning: overreacting
English equivalent: much ado about nothing
天涯海角 tiānyá hǎijiǎo (sky's edge, ocean's corner)
meaning: (referring to solemn vows) to the ends of the earth; the remotest corners of the globe; jumping-off place
天衣無縫 tiān yī wú fèng (heavenly cloth no seams)
meaning: seamless, flawless
10. uncategorized亂七八糟 luàn qī bā zāo (chaotic seven, eight rotten)
meaning: a huge mess
English equivalent: at sixes and sevens
對牛彈琴 duì niú tán qín (to cow play zither)
meaning: to address the wrong listener; to reason with the unreasonable; to preach to deaf ears, to talk over someone's head
English equivalent: to cast pearls before swine
塞翁失馬 (焉知非福) sàiwēng shī mǎ (yān zhī fēi fú)
meaning/English equivalent: a blessing in disguise
story:
en.wiktionary.org/wiki/%E5%A1%9E%E7%BF%81%E5%A4%B1%E9%A6%AC#Chinese畫蛇添足 huà shé tiān zú (draw snake, add feet)
meaning: unnecessary embellishment, adding something superfluous
English equivalent: gilding the lily
出生入死 chū shēng rù sǐ (be born enter death)
meaning: to risk one's life (a show of loyalty)
English equivalent: through thick and thin
學無止境 xué wú zhǐjìng (learning without endpoint)
meaning: knowledge is infinite
虎頭蛇尾 hǔ tóu shé wěi (tiger head, snake tail)
meaning: a promising beginning but abysmal ending
十全十美 shí quán shí meǐ (ten complete, ten beautiful)
meaning: perfect, flawless
雪中送炭 xuě zhōng sòng tàn (snow midst deliver charcoal)
meaning: assistance in the time of need
English equivalent: a friend in need is a friend indeed
打草惊蛇 dǎ cǎo jīng ché (strike grass, startle snake)
meaning: to unwisely alert the enemy, to prematurely show one's hand
井底之蛙 jǐng dǐ zhī wā (a frog at the bottom of a well)
meaning: a narrow-minded idea/approach to life
口是心非 koǔ shì xīn feī (mouth yes, heart no)
meaning: to say the opposite of what one really thinks
人山人海 rén shān rén haǐ (people mountain, people sea)
meaning: a huge crowd of people
束手無策 shù shǒu wú cè (bound hand, no scheme)
meaning: helpless, at a loss
隨時隨地 suí shí suí dì
meaning: anytime, anywhere
山窮水盡 shān qióng shuǐ jìn (mountain poor, water exhausted)
meaning: having run out of options
English equivalent: at the end of one's rope
明知故問 míng zhī gù wèn
meaning: to ask what one already knows the answer to
莫名其妙 mò míng qímiào (cannot name wonderful)
meaning: puzzling, baffling
進退兩難 jìn tuì liǎng nán (advance retreat both difficult)
meaning: in a bind
English equivalent: between a rock and a hard place
肝膽相照 gān dǎn xiāng zhào (liver gallbladder mutual reflect)
meaning: with deepest sincerity
胡說八道 hú shuō bā dào
meaning: talking rubbish/nonsense
胸襟廣闊 xiōngjīn guǎng kuò (lapel of gown broad)
meaning: generous, broad-minded
入鄉隨俗 rù xiāng suí sú (enter village, follow customs)
meaning/English equivalent: when in Rome, do as the Romans
11. non-four-word sayings無風不起浪 wú fēng bù qǐ làng (no wind, no waves)
meaning: there has to have been some portends about what's going to happen
English equivalent: no smoke without fire
百聞不如一見 bǎi wén bù rú yī jiàn (one hundred hearsays not compare to one look)
meaning/English equivalent: a picture is worth a thousand words; seeing is believing
不費吹灰之力 bù fèi chuī huī zhī lì (not waste blow dust strength)
meaning: effortless
English equivalent: as easy as pie; easy-peasy
TBC...
so, anyone have others/faves you'd like to share?
sources:
www.chinasage.info/proverbs.htmtw.18dao.net/%E6%88%90%E8%AA%9E%E8%A9%9E%E5%85%B8carlgene.com/blog/2010/07/20-actually-useful-chengyu-%E6%88%90%E8%AF%AD/