"Mac Daddy" or Mack Daddy, is a term used to describe a man with an unusual power over women, and is derived from the French and later Louisiana Creole patois term "maqereau", which means "pimp". Adding "daddy" makes it mean "top pimp". The '70's black-exploitation movie "The Mack", a dramatization of the life of a street pimp, furthered the popularity of the term in urban America. This use of "mac" is quite different from the Scottish/Gaelic term "mac" (son of) used to address an unknown man.
Freddy got five chicks on the south side alone… he 'da mac daddy!