I heart 3RD ROCK FROM THE SUN: Episode Guide 2

Season 4 -- Two-Faced Dick

The Big Giant Head grants Sally's three-year-old request for a "gender reassignment" - and switches her body with Dick's. Responding to a three-year-old request from Sally that she be given a male body, the Big Giant Head switches Sally's body with Dick's. Each of them has to cope with all the thorny details of gender reassignment, including such specifics as how to deal with men's catcalls, and where to find cute shoes in Dick's size. Plus, each of them has to successfully maintain the other's romantic relationship. They each get as far as a kiss, but before things go any further, their request to switch back is granted, leaving them both far more knowledgeable about what it's like to be a member of the opposite sex.