An upside-down keymap for OS X. Practically useless, since you also have to think backwards when typing. (It may come in handy around the beginning of April, though.)
:(sʞɔıɹǝʌɐW X SO) suoıʇɔnɹʇsuı uoıʇɐllɐʇsuI
- Open ~/Library/Keyboard Layouts/
- Save the keymap file in there
- Log out, log back in
- Open Keyboard preferences, switch to Input Sources
- Click + and select 'Others'
- Select and add Upside-down
¡unɟ ǝʌɐH