WordNet (r) 3.0 (2006):

city slicker
    n 1: a city dweller with sophisticated manners and clothing
         [syn: city slicker, city boy]

Moby Thesaurus II by Grady Ward, 1.0:

25 Moby Thesaurus words for "city slicker":
   big-city man, bourgeois, burgess, burgher, city dweller, city man,
   cosmopolitan, cosmopolite, exurbanite, man of experience,
   man-about-town, oppidan, slicker, sophisticate, suburbanite,
   townee, towner, townfolk, townfolks, townsman, townspeople,
   townswoman, urbanite, villager, villageress