They like to run around shrieking the most hilarious mispronunciations. The kids, I mean, not the tourists. Though sometimes it seems like they do, too.
Try this one: "Chwaraeasoch chwe chŵn chwaraegar chwe chwibanau chwedlonol i chdi." Or... "Mae Llewellyn y llyfrgellydd o Lanelli wedi llyfu llawer o lyfaint."