all fools' day
  愚人節
  All Fools' Day The first day of April, a day on which sportive impositions are practiced.
  The first of April, some do say,
  Is set apart for All Fools' Day.   --Poor Robin's Almanack (1760).
  ◄ ►
  All Fools' day
       n : April 1; celebrated by playing of practical jokes [syn: April
           Fools', April Fools' day]