If you're gonna downvote something straight into the basement, some kind of reply is appreciated...
EDIT: logical conclusion: I actually managed to send HN'ers into an illogical blind rage. props to me. Oh look, there goes my respect for the place. <- did I get it right?
1) Very often clever quips, even if they are funny, distract from the conversation. Being overly strict about this helps keep the place from devolving into a jokefest like so many other forums.
2) Some people will vote you down for complaining about downvoting.
I sympathize with both of these rules of thumb, for what it's worth.
EDIT: For some reason the "reply" link below your post is missing for me, so I'll just clarify a bit here, more than I usually would since this is a thread about gaming social norms. ;)
Rule of thumb #2 also stands for asking for clarification about downvoting. Especially when you do it 3 times: by editing your original post, then replying to it, and then editing the reply. And especially when you seem defensive about it.
Keep in mind that if you get "downvoted into the basement", it's not just one person downvoting you, it's at least 5. You've probably violated some implicit norm. Repeatedly asking for clarification is kind of its own awkward thing in these circumstances (especially with some manners of asking).
Imagine if you make a joke in a group of friends and people obviously don't think it's funny. It's not cool to demand an explanation, like people somehow owe it to you to explain why and how you screwed up. Usually better to suck it up and move on, and try to learn from the experience.
You got a subtle reply from mbateman, but I'll add two points. First, it's a good idea to read http://ycombinator.com/newsguidelines.html; notice the penultimate one. Second, the downvoting of quips on HN needs to be understood in relation to Reddit, where nearly every popular thread quickly becomes dominated by a long chain of (often genuinely funny) wisecracks. Experience shows that this pattern drowns out substantive discussion, and HN is all about the latter. What people here are downvoting is not merely the individual wisecrack, but that whole pattern. It's a kind of prophylaxis. Lack of a sense of humor has nothing to do with this; it's a conscious tradeoff.
This kind of downvoting has another virtue, which is that it's silent. If it added noise to the conversation, that would be ironic -- and annoying, too. If one thing's worse than misdirected wisecracks it's humorless metadiscussion. I'll stop here. :)
Humor is fine, but stuff that sounds childish (4chan memes, fart jokes), or sarcastic tends to get downvoted. IMHO with good reason: sarcasm isn't a good way to make a point. Sarcasm is about making your conversation partner look like a tool instead of bringing up an actual justification for your point of view. Good debate should be done with a "cold, hard facts" attitude and a non-aggressive tone. It's fortunate that even with the constant change in the user base, HN still strongly encourages moderate posts.
I actually upvoted you because I think -4 is overkill, but I must admit I don't get the point of your post. I don't personally see it as sarcasm... just a failed joke?
edit: I'm not sure if people don't like my sarcasm, don't understand what I actually meant, or are just close-minded.