The Collaborative International Dictionary of English v.0.48:
jerkoff \jerk"off\, a. A lazy, foolish, stupid, or otherwise contemptible person; -- an offensive and disparaging term. [vulgar slang] Syn: jerk. [PJC]WordNet (r) 3.0 (2006):
jerk-off n 1: terms of abuse for a masturbator [syn: tosser, jerk- off, wanker]