The Collaborative International Dictionary of English v.0.48:
Tosser \Toss"er\, n. One who tosses. --J. Fletcher. [1913 Webster]WordNet (r) 3.0 (2006):
tosser n 1: terms of abuse for a masturbator [syn: tosser, jerk- off, wanker] 2: someone who throws lightly (as with the palm upward)