A pretty crazy bug report was filed with Apple on Thursday afternoon. According to a copy of the bug on Open Radar, all you have to do is type the text below into almost any window in any app on OS X to immediately crash the app. We managed to crash Tweetbot, Safari, Chrome, TextEdit, and more with this bug, but a few rare apps seem to be immune. This bug is so pervasive that typing it into this post crashed Safari and Chrome, so we embedded an image of the text below (apparently GIMP is one of those apps that can handle it safely).
In order to make this happen, you’ll need to type the above phrase into just about any OS X app, including all three slashes and the capital F. The bug report filed with Apple speculated that this is caused by the spellchecker built into OS X, but we find this theory unlikely since it appears to affect text boxes such as the Safari location bar that don’t include spellcheck. The bug affects all Macs running Mountain Lion, but it does not have any effect on Lion or Snow Leopard.