Immortal, perhaps, but unknown to me (tho' VW herself isn't)!
Better add a joke, and this one gains a bit from context (as well as a knowledge of Scots pronunciation). It works best if someone in a group asks if anyone knows "a Dirty Joke", to which the reply "Joke the Coalman" seems either senseless or funny, depending on whether you recognise that in some places the name "Jock"...

Actually, that joke is now, here at least, clearly archaic.