There is one major problem with the panic button.
If someone busts in and you do manage to hit it and navigate away from this forum, the other page doesn't load instantly. Especially if it's something like Youtube or MySpace.
Another problem is this. From my experience, people will stand at the door and talk to me, they won't come in. So they can't see what's really going on (unless I had a huge image of furry porn or something being displayed). They can't see what tabs you have open, and with my FastDial plugin suggestion earlier, they won't think twice about it.
But usually, if a web page is loading when they come in, they won't think twice about it anyway. I mean, the World Wide Web is slowly turning into the World Wide Wait.