(UPDATED) In spite of what you're apt to read on any of over 10,000 web pages, the word dork does not mean (and has never meant) whale penis. I defy anyone who claims it does to show it defined as such in any respectable dictionary past or present, or used as such in any reference work or novel about whales or whaling published since, well, the dawn of publishing. (Please note that this article was originally posted in May 2009 and no such evidence has been produced to date.)
Though its precise origins remain somewhat obscure, etymologists do generally agree that dork — typically defined as "a stupid, foolish, or inept person" — has only been in common usage since the 1960s, and is most likely a variant of dick — which is, in fact, a slang term for penis, but not specifically that of a whale.
For example, The Concise New Partridge Dictionary of Slang and Unconventional English (2007) defines it thus:
dork noun 1 the penis US, 1961. 2 a socially inept, unfashionable, harmless person US, 1964.
As in every other source I've checked — including the ultimate authority on English word origins, The Oxford English Dictionary — there is no mention of whales. None.
For good measure, I posed the question to several whale experts — including Professor C. Scott Baker of the OSU Dept. of Fisheries and Wildlife, John Calambokidis, senior research biologist and co-founder of Cascadia Research, Phillip Clapham of the National Marine Mammal Laboratory, and author Richard Ellis (The Book of Whales, Men and Whales, Encyclopedia of the Sea, etc.) — all of whom told me they had never seen nor heard the word dork used in reference to a whale's reproductive anatomy. Ever.
Further adventures in epithetymology:
• Origin of the F-Word: "Fornication Under Consent of the King"
• Origin of the S-Word: "Ship High in Transit"
• Origin of The Finger: "Plucking Yew"
In answer to those who would seek to rebut these findings by arguing that if enough people use the word dork to mean "whale penis" then it's a valid definition, here's what's wrong with that argument: the phenomenon we're discussing isn't people using the word that way — nobody really does — it's people claiming that dork means "whale penis" on the basis of no empirical evidence whatsoever. It's just another false Internet factoid.
All of which is by way of saying that if you ask me, the rightful definition of a dork is the sort of person who would make up something like this: Why Is the Ocean Salty? Whale Sperm!