April Fools' Day; April fool
Refers to the day itself or the prank; synonymous with エイプリルフール.
See also: エイプリルフール
Today is April Fools' Day, so be careful.
He played a prank on his friend for April Fools' Day.
More common loanword for April Fools' Day; 四月馬鹿 is a native Japanese equivalent.
Compound of 四月 (April) and 馬鹿 (fool), a calque or native equivalent of English 'April fool'.