The Collaborative International Dictionary of English v.0.48:

Stooper \Stoop"er\, n.
   One who stoops.
   [1913 Webster]

WordNet (r) 3.0 (2006):

stooper
    n 1: a person at a racetrack who searches for winning parimutuel
         tickets that have been carelessly discarded by others
    2: a person who carries himself or herself with the head and
       shoulders habitually bent forward