Which dog trainer advocates "nose flicks"?

I don't see how ''nose flicking'' would be needed to train a dog. Train a dog to do what? That's what I don't get. I've VERY lightly tapped my dog on the nose before to get her nose out of something like a bag, my shirt, dresser, etc. but not flick it. Don't know where the method came from either nor when it would be needed.