His pose defies gravity.
Or the picture is turned.

It's a strong gust of wind he's leaning on. Those flying leaves make it kind of obvious. But I suppose that is indeed one way of defying gravity.

Kraco said:

It's a strong gust of wind he's leaning on.(...)

Lol! You made my day. Or he's doing Michael Jackson's moves, the Moonwalk.

Or he's doing Michael Jackson's moves, the Moonwalk.

That's actually a much better (that is, funnier) explanation especially knowing his personality.