我們平時說某人行為做事很愚蠢，可能會用“沒腦子”或者說某人的腦子是某種動物的腦子，總之，就不是正常的human brain。在英語里，他們把“愚蠢的”行為稱為harebrained（野兔腦子），估計跟咱們說的“豬腦子”意思差不多。至于后來為什么演變成 hairbrained，看了下面的解釋就明白了。
    The first use of harebrained dates to 1548. The spelling hairbrained also has a long history, going back to the 1500s when hair was a variant spelling of hare. The hair variant was preserved in Scotland into the 18th century, and as a result it is impossible to tell exactly when people began writing hairbrained in the belief that the word means "having a hair-sized brain" rather than "with no more sense than a hare."
    Harebrained的用法最初見于1548年。而hairbrained這個拼法也有很長的歷史，可以追溯到16世紀，那時候hair是hare的另一種拼法。蘇格蘭一直將hairbrained這個拼法保留到18世紀，因此，人們到底從什么時候開始使用hairbrained，意即“頭發(fā)絲那么細的腦子”，來取代原本表示“跟野兔一樣沒腦子”的harebrained也就無從考證了。
    While hairbrained continues to be used, it should be avoided in favor of harebrained which has been established as the correct spelling.
    雖然hairbrained還在繼續(xù)使用，但是，既然harebrained是最初的正確拼法，我們就應(yīng)該避免這種混淆使用的情況。