Some people have a low bar for fun, for example, learning something new that connects to something they already knew, and saying to themselves, "Neat!"
I didn't mean to poke fun, but I can see now that it triggered some pretty hard responses.
I should have attempted to be clearer - I specifically only meant to question the "fun" part. I didn't mean to suggest it's not a "good" fact, or a good "random" fact. Sure, it'd be great in a discussion as you describe.
Trying to think of some analogy to illustrate my point - imagine watching a movie, and someone says: "fun fact, actor xyz is also in movie abc." I, personally, would think: where's the fun part of this fact?
Fun facts need some oomph! Some surprising bit to them, something you wouldn't have seen coming. "Actor xyz showed up unannounced at my cousin's wedding for reason abc", would be a "fun fact".
Or you're listening to a Björk album with a friend, and half-way through he says: "oh, actually, fun fact, I once played on stage with Björk during a festival in Iceland", and he proceeds to launch into a few anecdotes.
Here, the fact was: "someone who wrote a seminal paper in AI is working in an AI company". I, personally, said to myself: oh, right. What's the surprise?
Apparently that was seen by some as an uncouth and uncultured reaction (not you though, you were very polite, hence my responding here). Oops.
One of the things I like about HN is the civilised discourse and your reply is a great example of that.
I get what you mean re the unexpectedness of a fact and level of fun, too. So thanks for explaining -- makes sense and I understand your original comment better :)
The opposite of the fantasy football subreddit is probably moreso someone making minor specific side-points about language use and expecting others to read carefully, i.e. me in my initial comment, rather than the person misinterpreting them and making sarcastic remarks. Who, in actual fact, is probably more closely mimicking the behaviour of such subreddits.
It was an amusing remark though nonetheless, out of all of them it's the one that gave me a chuckle.
I responded to the general responses just above anyway, if you're interested.