I was briefly in the Game Development chat (DO NOT CLICK HERE OR YOU WILL BE TRANSPORTED INTO THE NINTH CIRCLE OF HELL) early today, and although I'd closed the tab, i noticed I was still listed as in that room.
So I decided to leave. I clicked the little icon and then OK.
Sure enough, I left Game Development...
But only for a few seconds. Within five seconds, it mysteriously reappeared!
For the avoidance of doubt, I left all other chat rooms as well, and successfully. It's only Game Development that I can't leave. I have no other tabs open with chat windows.
Interestingly, sometimes I can leave it, or so it would appear - but only as long as I don't click Rejoin Favorite Rooms. If I am stupid enough to do that, I get rejoined to it, even though it is not one of my favorite rooms! If I am in some of my favorite rooms, then I just get rejoined to Game Development immediately. (Note that some of my favorite rooms are private rooms and I'm not showing them to all of you.)
I am using Firefox 26 on Linux (Fedora 20, KDE). Also, to the best of my knowledge, I have not attempted to parse any HTML with regex lately.