When the Watsons decide to zip their porcine wonder into a formfitting princess dress for Halloween — complete with tiara — they are certain that Mercy will be beautiful beyond compare. Mercy is equally certain she likes the sound of trick-or-TREATING and can picture those piles of buttered toast already. As for the Lincoln Sisters next door, how could they know that their cat would get into the act and lead them all on a Halloween "parade" of hysterical proportions?