The Collaborative International Dictionary of English v.0.48:

Punch \Punch\, n. [Abbrev, fr. punchinello.]
   The buffoon or harlequin of a puppet show.
   [1913 Webster]

   Punch and Judy, a puppet show in which a comical little
      hunchbacked Punch, with a large nose, engages in
      altercation with his wife Judy.
      [1913 Webster]