This has obviously been going on for a very long time without my having picked up on it before. I've only just begun to notice it, and I'm very sorry I have, because I'm never going to be able to ignore it now and it's driving me nuts. The phrase is "Tell you what ..." or "You know what? ..." or "You know something? ..." I hear it on TV or radio a dozen times a day, used by everybody from interviewed politicians to actors in comedy shows and dramas. The useage is not a new thing and it's not confined to the UK - it's cropped up in many episodes of old 1960s' British TV shows and even in a couple of old American 1950s' films that I've been watching lately (thanks to having no energy to do anything else due to having both a strained shoulder muscle and a lousy cold!).
Has anyone else noticed it? Please accept my apologies if you hadn't but, because I've mentioned it, you now begin to do so and can't get it out of your head!

"Progress might have been all right once, but it has gone on too long." ~ Ogden Nash