Okay. I'm going to try one more time to describe it, and if I can't I may be able to get a picture of it tomorrow - or some time this week.
Make your hands into fists, like you do when you're riding, but keep your thumbs pointing up. Take a crop, insert crop in between fists and thumbs, close thumbs. You have to hook your thumbs around to keep the crop there. You should be able to slide your hands around, but the thing is, you really just don't while you're riding like that. It's like magic!
I hope tealamutt and I are talking about the same thing. If not, I'd be interested to see what she has to say.