It's very very similar to a whippet. And the swirlies you are talking about are very similar to the different colors you would see swirling around in the air when you are tripping. And this didn't start but maybe two, 2.5 years ago, LONG after I started smoking weed (I don't smoke anything else and never have), and about 2 years after I stopped doing anything hard. Haha...that's kinda how I found out about it. I was standing up and did it and it was starting to feel really good. The next thing I know I was waking up in the floor, the chair I was holding onto when I stretched was on its side, and I had a pump knot on my head. I quickly realized that I had passed out, took the chair with me on my way down, and hit my head on the arm of the futon. Now since I know what happens, I'm either usually sitting down when I do it, or if I'm standing, close enough to where I can sit down if I need to. Trust me, I've given this plenty of thought.