I've grown so tired of sarcasm. Online and in real life people are often saying the exact opposite of what they mean. We have to pick up the sarcasam to truly understand.
Agreed, this is why I didn't want to take a hard position on downvoting someone for missing the sarcasm. We're in a public forum which crosses cultural boundaries. I see the argument for both sides.
Although I lean more towards downvoting as the majority of people on HN will get the joke and it's an opportunity to learn for those unfamiliar with the mainstream culture.