Re: Double down?
> "Double down" makes no sense
Double Down is a bet in Black Jack, where it does make sense. It appears to have entered the lexicon as a synonym for Double Up much the same way that "I could care less" has become an acceptable* alternative for "I couldn't care less."
> 'arry 'oudini sat in the 'erb garden - Yes or No?
Are you French? I had a French colleague once who could not voice the Haitches in any word. Not for love nor money. I have met nitwits who pronounce the Haitch in Herbs and Spices. My SiL's father is Herb(ert), pronounce the Haitch please. AFAIK Harry Houdini pronounced the Haitches in both of his names, but he's not around for me to ask. I believe I've heard Ms. Rowling (rhymes with bowling) pronounce the Haitch in Harry Potter.
*Well, acceptable for some perhaps. Probably only to those who use it.