Standing or sitting in the sections between carriages on a busy train, 'cos all the seats are taken.
Usually on an unplanned long-distance trip, where the seats are all booked in advance.
About as far from first class as you can get without going outside the train.
After missingthe train we'd booked seats on, we had to travel corridor class until we got to Birmingham.
1. A line in football exactly between the back line and the goalkeeper, usually roughly level with the six-yard-box. Any cross into the Corridor of Uncertainty will cause all sorts of panicky and comedy defending as neither goalie nor defence are sure to come or stay.
2. A line in cricket, when the ball pitches usually on a length, just outside the batsmans off-stump. It is such a good line that it leaves the batsman unsure of whether or not to play a shot, and usually results in either an edge, a play-and-a-miss or some other form of comedy cricket.
4. A womans anus. Do you dare venture into the Corridor of Uncertainty?
Ooh, he's put that cross right along the Corridor of Uncertainty and caught the defence in one dilly of a pickle!
Fletcher: "If you keep putting the ball into the Corridor of Uncertainty, you'll get an edge for a wicket eventually."
Harmison: "OK, but what if I just bowl at second slip?"
Paul: "Let's go this way. It's a short cut."
Mike: "No, I can't see down there - it's a Corridor of Uncertainty."
James: "Let's have sex!"
Milly: "We can't, it's my time of the month!"
James: "No worries, I'll just put it in the Corridor of Uncertainty."
Milly: "Ouch!"
Acela Corridor Galaxy Brains is a phrase coined by the renowned economist and scholar in Sino-US-Europe study Christopher Balding to refer to people from Boston to the DC along the east coast who have never left their towns such as Cambridge, the borough of Brooklyn, or Georgetown but think they know enough to run the world such as journos or tankies. Acela is the "high speed" train line with a top speed around 90 mph for brief stretches.
China, with Acela Corridor Galaxy Brains' assistance, is pushing this nonsensical line that "let's repair the relationship but not talk about anything of importance."