Following on from the massive success of the Cardiff Bus Song, here's another transport-related bit of fun. Whether the expression is unique to Kairdiff is not the point. To us, it's as local as Clarke's Pies and Billy the Seal: when you hears it, you knows yer in the 'Diff. Next time you hop off a bus or get out of a cab*, don't say thing – just flash this t-shirt.
(*You'll prob'ly still have to pay, mind you.)