While I'm on the subject of nerdy London Underground facts, have you noticed the mysterious abbreviations above the doors of tube carriages? You haven't? Just me then? Well, take a look next time you're on the tube - there, just above the doors, a series of letters: TCCOS or Com COS or something equally unintelligible. For years now, I've been trying to figure out what they stand for and now, thanks to the internet, I have found out. For instance, TCCOS stands for Traction Control Cut-Out Switch. Whatever that is.

OK, so I now know what the letters stand for, but I'm none the wiser as to what they actually mean. Something, perhaps, a little like this:

CIC	Coupler Isolating Cock: I picture a drunk couple coming home from after-work drinks. "Go on," she says, fumbling with his flies, "no-one's looking, get yer cock out!"
Con G	Control Governor: A strict, prim middle-aged lady in buttoned-up grey tweed coat and shiny black boots, umbrella on her lap, lips compressed.
Com: G IC	Compressor Governor Isolating Cock: "Young man! Your penis is sticking out." "Madam, you flatter yourself - it is hanging out!"
TLIC	Train Line Isolating Cock: "I said put your pennies on the line!"
WWIC	Window Wiper Isolating Cock: Ow!
PWR	Passenger Warning Relay: "Apologies for the delay; there's some fool with a baton on the line."
SAPB	Spring Applied Parking Brake: As opposed to the autumn applied parking brake, more commonly known as "the wrong kind of leaves".