My school in north Staffordshire used to play host to foreign students, usually French, who would spend a year there helping to teach their own native language. One year we had a lad called Francois, who reckoned he was pretty good at spoken English. To reach us he caught a train to Stoke station and then found a bus, and the first words spoken to him in Staffordshire were by the bus conductor, who welcomed him on board with the friendly greeting, "Ey-up, squire!" At this point, it dawned on Francois that his command of collquial English was not as great as he had supposed. He had to ask us what exactly "Ey-up squire" meant, and after a little thought we had to tell him that it didn't actually mean anything at all.
That summer, Francois was watching a game of school cricket with some bemusement when John, who prided himself on being a straight-talking, no-nonsense (and foul-mouthed) working-class Yorkshireman, decided to take him in hand. "Here, Francois!" he said, "Come with me: I'll explain about cricket!" We watched them walk around the boundary edge, with John making expansive gestures. Afterwards we asked, "Well, Francois? Do you know all about cricket now?" Francois looked a little downhearted. "I could not understand a single word, except for zee bloodys and zee f***ings!" he said sadly.