Oh wow—I'm even less original than I thought! They even had the same name!
Thanks for these omoikane and bazzargh (and the others both here and on Twitter), I'll have to add an addendum to the blog post with links to all the other fun related examples.
Previously (2009): https://twitter.com/selfrefer/status/3128391843 https://twitter.com/spoonhenge/status/2878871344 https://news.ycombinator.com/item?id=743144
(last 2 were self-referential at the time, but then twitter changed the rules for linking; I recalled seeing these at the time)