It was a pun on a pejorative use of the word - if you disagree, look up "pejorative".
At the risk of seeming "PC" to oversensitive folks, using social identities as pejoratives is inherently insulting; you're associating their racial/sexual/etc. identity with something undesirable, even if you don't think of it as a slur. "Gay" to mean stupid or annoying is of a piece with terms like "gyp", "indian-giver", or "nigger-rig".
This has less to do with political correctness, and more the idea that posts like yours are just kind of annoying. The tone makes the site seem a lot less civil. It didn't add anything to the thread. Now all we have is you acting very annoyed that we didn't like your joke.
Humor is encouraged on Hacker News, but only when it is actually funny. Your joke wasn't funny.