Hola Bruno,
Parece que se refiere a un verso de una canción infantil tradicional irlandesa (canción completa en el enlace abajo):

"...Who put the overalls in Mrs. Murphy's Chowder?
Nobody spoke so I shouted all the louder.
***'Tis an Irish trick 'tis true, but I could lick the Mick*** that threw the overalls in Mrs. Murphy's Chowder. ..."

Source: "The Book of KidsSongs 2: Another Holler-Along Handbook" by Nancy and John Cassidy, Klutz Press. ISBN 0-932592-20-1

Por otra parte "lick" es slang dublinés para "pegarle" o "defraudar a alguien" y "Mick" es una manera despectiva de llamarle a una persona originaria de Irlanda.

dirty trick = mala jugada
-- Source: Diccionario Espasa Concise © 2000 Espasa Calpe

"***Mick/Mic/Mc*** Irish Many Irish surnames begin with "Mc" or "Mac." Many Irish are also named after the famed Michael Collins, making Michael (Mick) a very common name. Not as derogatory as Paddy...."

http://www.angelfire.com/geek/APRACE/glossary.html

Buena suerte y saludos del Oso ¶:^)




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Note added at 2005-06-13 02:03:27 (GMT)
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Aquí esta la referencia de \"lick\" que no incluí arriba:

\" ***TO LICK. To beat**; also to wash, or to paint slightly over.
  I\'ll give you a good lick o\' the chops; **I\'ll give you a good
  stroke or blow on the face**. Jack tumbled into a cow
  t—d, and nastied his best clothes, for which his father stept
  up, and licked him neatly.—I\'ll lick you! the dovetail to
  which is, If you lick me all over, you won\'t miss—. \"

http://www.harvestfields.netfirms.com/etexts/31/13.htm