When I was young I used to use this technique quite a lot. I've never read it on any techniques pages, so I guess it's pretty unique. But it's works really well.
What you do is, find yourself somewhere where you can hold your self in mid air, ie. a chin-up bar or something. For this to work though, you also need some sort of vertical pole or (as I liked to do) a tree, where you grab onto two branches and use the trunk as the vertical pole. The vertical pole (or whatever you are using) needs to be lined up so that it it in line with the centre of your body. It also needs to be firm and strong to withstand pressure.
To start off you need an erection. It's quite simple really. Pretend you are doing chin-ups while at the same time rubbing your erect penis over the vertical pole. You don't need to do full chin-ups as you are only really slightly moving your body up and down the pole. It is better to do this with underpants on so that you can get the full rubbing effect on your cock. When you rub your cock up and down the vertical pole or trunk, it works best if you are rubbing the underside of your erect cock. This is why wearing underpants helps and it keeps the cock upright.
There are various ways you can rub it, and how fast you want to do it. But the difficulty of muscling your way to pulling your whole body up and down, when at the same time, getling great sexual feelings through your penis, contributes to creating a great orgasm when you climax hanging in mid air.