The real meaning is just how it is used in everyday speech, that being:
1. a stupid or ridiculous person; jerk; nerd.
2. Vulgar. penis.
It is popularly asserted that the term originated as whalers' occupational slang for the penis of a whale, and by transfer became an anatomical insult, undergoing subsequent generalization and amelioration to its present meaning. The current state of evidence suggests that this is a case of folk etymology, as no solid documentation has been advanced for the use of the term in this context. One of the earliest documented uses of the word "dork" is a 1961 publication (referencing 1953), in which the meaning is clearly penis, but with no particular reference to whales. Instead, the term may be merely a minced oath variant of "dick", a vulgar term for a human penis.