Artificial intelligent assistant

All Fools' Day

All Fools' Day
  [prob. orig. with jocular reference to All Saints, All Souls.]
  A humorous name for the 1st of April; the day popularly appropriated to practising upon one's neighbour's credulity. (Only of modern use.)

1712 Swift quoted in Hone Ev. Day Bk. (1826) I. 205 ‘A due donation for All Fool's Day.’ 1760 Poor Robin's Alm. in Brand Pop. Ant., The first of April some do say Is set apart for All-Fools Day. 1777 Brand Pop. Ant. 398 All-Fools' Day, a corruption it should seem of Auld i.e. Old Fools' Day. 1823 Lamb Elia (1868) 65 All Fools' Day. The compliments of the season to my worthy masters.

Oxford English Dictionary

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