Comes in two sizes: circus and cramped pit. Neither comes with windows. A place where you are supposed to do your "work." But what with students banging down your door for office hours (I hear you laughing sarcastically, reader!) and your office mates screaming out the latest posts on Facebook, it's kind of hard to get things done. Many grad students choose to eschew this rat hole and camp out in a coffee house, where at least there's good music and if you sit in the way way back behind that tall guy with the hat maybe your students won't be able to find you.
Sample sentence: When I'm in my office, I can't tell if it's night or day.