At least on Reddit people make jokes. At one point the most-gilded comment ever was a (honestly, pretty funny) one-line joke reply to a paragraph long heartfelt comment about grief and loss.

Here it's a loose game of word association. For example, title says "GNU" in any context so we get 300 comments with unrelated anecdotes about Stallman. The comments section becomes stories about whatever random nonsense is in the top 2-3 comments. When it was being published, n-gate[0] was great at highlighting this.

[0] http://www.n-gate.com/hackernews/