Humans have been cracking open skulls since Neolithic times, with some surprisingly specialized tools left behind during that mind-shatteringly long history. Archeological digs in South America have unearthed surgical tools made of bronze and volcanic rock, seemingly designed to drill or scrape into heads and prod the sensational goop within. But Chinese has a few less threatening ways to open one's head hole.
In traditional Chinese medicine the brain is less of an object of focus, since the body is seen as more of an intertwined system, with the organs working together to create intelligence. Despite this, the brain, or skull, 脑袋 (nǎodai) is heard often in day-to-day speech. One common saying in Chinese, however, seems right at home with the Western history of trepanning: 脑洞大开 (nǎo dòng dà kāi), "head hole wide opened", refers to the type of madness evoked by a book or movie when one's imagination is set free, a sort of artistic inspiration where your mind flutters in and out of the escape hatch left in the skull.
Commenting on Liu Cixin (刘慈欣)'s famed sci-fi trilogy The Three-Body Problem (《三体》), one Weibo user says: "这些书为我打开了数个世界，不，不是世界，是星系？是维度？是空间？是脑洞大开。(Those books opened a number of worlds for me—no, not worlds. Galaxies? Dimensions? Space? They opened my head hole)."
The saying overlaps with "open your mind", much in the same way a book would "open your mind". But, it wouldn't be proper to say "open the hole in your head", when you wanted someone to be more acquiescent to an unusual idea, like, say, the dubious merits of skull perforation, or perhaps something that was merely progressive such as gay marriage. In that case, it would be more appropriate to say "想开一点儿" (xiǎng kāi yì diǎnr), or "think openly".
"脑洞大开"的意思与"open your mind"重叠，两者很大程度上都含有某本书将"打开你的视野"的意思。但是，当你要别人接受你另类的观点，比如，脑袋穿孔术令人质疑的优点或者仅是一些开明的想法，如同性婚姻，说"打开你的脑洞（open the hole in your head）"却是不妥的。这时候，更适合说"想开一点儿"。
People often say a song's lyrics can open their head holes, 这段歌词让我脑洞大开 (zhè duàn gēcí ràng wǒ nǎodòng dà kāi). In English similar expressions have actually appeared in songs: "Ooh, boy d'you miss me like a hole in the head," goes the chorus of the Sugababes 2003 hit single "Hole in the Head".
人们经常说"这段歌词让我脑洞大开"。英文歌曲中实际上也有类似的表达，"Ooh, boy d' you miss me like a hole in the head"，这句歌词来自于甜心宝贝合唱2003年的热门单曲"Hole in the Head"。
Returning to the notion of madness, one Baidu user cleverly postulates that the "hole" is where the water gets poured in when one is suffering from 脑子进水 (nǎozi jìn shuǐ), or "water in the brain", a clichéd term for acting crazy. Be it books, movies, or songs, we are all thankful for these inspirational little fissures.
Translated from: The World of Chinese