Since when was humor disallowed on HN? I think a good unique joke is relevant, as it gets us all excited about the topic. Maybe it doesn't directly add factual information to the subject, but it improves the mood and makes learning more fun.

I mean, sure, we don't want it to be like Reddit, where it's a race to post the cleverest puns, but a chuckle once in a while shouldn't be frowned upon.