Source : Webster's Revised Unabridged Dictionary (1913)

Merry-andrew \Mer"ry-an"drew\, n.
   One whose business is to make sport for others; a buffoon; a
   zany; especially, one who attends a mountebank or quack
   doctor.

   Note: This term is said to have originated from one Andrew
         Borde, an English physician of the 16th century, who
         gained patients by facetious speeches to the multitude.