Uses Unicode to make text look like it's been rotated 180 degrees.
I got the idea to do this years ago from a LiveJournal entry. Per request, I'm making this vaguer, but I owe a big thanks to the author for the fun idea (and the most interesting mappings) as well as for their patience for the noise and chaos I sent their way.
Thank you also to Brook Monroe, Tim McCormack, Glards, and Yeeliberto amongst others for further suggestions.
Formatted with https://prettier.io/.