How many other meme modes exist? I dug up the earliest commits I could find, and apparently one of the earliest hooks was "protect-innocence-hook": https://twitter.com/theshawwn/status/1327459335245422597
If the buffer's filename is "sex.6", it asks whether the user is over 18. If so, it renames the buffer to "celibacy.1".
Apparently it was in the file lisp/play/meese.el. Emacs archaeology is more fun than it should be.