April Fool's Day is on April 1.
愚人節的來源英文版：
"April Fool's Day" is a lying festival that appeared after the religious revolution in the 15th century AD. At that time, Philip II, the king of Spain, established a "heretic Inquisition".?
As long as he was not a Catholic, he was regarded as heretic and was sentenced to death on April 1 every year. The subjects feel very terrible, so they take lying and joking as their pleasure every day to dilute their fear and hatred of the rulers. Since then, it has been used for a long time and evolved into today's "April Fool's Day".
擴展資料：
每年的四月壹日，是西方的民間傳統節日——愚人節（April Fool's Day），也稱萬愚節。對於它的起源眾說紛紜：壹種說法認為這壹習俗源自印度的“詮俚節”。該節規定，每年三月三十壹日的節日這天，不分男女老幼，可以互開玩笑、互相愚弄欺騙以換得娛樂。
較普遍的說法是起源於法國。1564年，法國首先采用新改革的紀年法——格裏歷(即通用的陽歷)，以壹月壹日為壹年的開端，改變了過去以四月壹日作為新年開端的歷法。新歷法推行過程中，壹些因循守舊的人反對這種改革仍沿襲舊歷，拒絕更新。
愚人節這天玩笑只能開到中午12點之前，這是約定俗成的嚴格規矩。過了中午還找樂子的人是壹個比被他取笑的人還大的傻瓜。過了鐘點還開玩笑的人會立刻碰釘子，自找沒趣兒。有壹首小詩是這樣描述的：愚人節已過十二點，妳這個大傻瓜來得晚。待到來年愚人節，妳將是最大個的大笨蛋。