The execution of this cast as well as its variations and uses are explained perfectly in the Sexyloops fly casting manual. Of all its applications, here's one that will allow you to present the fly from an angle that is practically impossible any another way (well, for me, anyway). This cast attracts a lot of admiration and applause. It's won me quite a few beers. Worthwhile learning.
New application: To present the fly from a very difficult angle for any other cast from a certain position (imagine you're wearing a suit and tie and you don't want to get wet above your knees because you're going to a wedding).
If it doesn't come out right, it's because...