Now here's a thing; my grandfather was Welsh (from Llanelli) and he had relatives in the north of Wales. He said that, actually, the language of north and south Wales was so materially different that the two sets of relatives had to speak to one another in English. So, this Welsh they teach in schools these days isn't actually an original Welsh language, but rather a blend of northern and southern Welsh.
Finally, here's the Viz Profanisaurus definition.
Masturbation by frottering with a leek while listening to a male voice choir.
I also seem to recall that "speaking Welsh" is a euphemism for throwing up. A lot.
Just sayin', is all...
UPDATE: there's a mildly angry response...