The name given, in Glasgow at least, to a Black Hackney Taxi Cab. You know, the stereo-typical taxi that you see in London. They are the biggest rip off you'll encounter after a night out on the town, charging at least £20 for a 4 mile journey, claiming that there is a "Boundary Charge" and you've just travelled through three boundaries. Which is complete bollocks, and I should know, as my wee brother works for the company that paints them, and he knows FOR A FACT that there is no legal precedence for the "Boundary Charge". So if you're ever in the UK, NEVER get a Black Hack. Go for a local firm, they're usually half price.
"Man, I ended up walking half-way home last night, the Black Hack raped a hole in my wallet before I left the city centre!"