From The Collaborative International Dictionary of English v.0.48 :
dork \dork\ (d[^o]rk), n.
1. a person who is stupid, socially inept, or ridiculous; --
always used disparagingly. [slang.]
Syn: nerd; jerk. [PJC]
2. the penis. [vulgar slang]
[PJC]
From WordNet (r) 2.0 :
dork
n : a dull stupid fatuous person [syn: jerk]