scissors hip key:

imagine a string hanging from the ceiling that you go to cut halfway up. you take a pair of scissors, and are about to snip the bottom half off the string. now imagine that instead of closing the blades you rotate your wrist a half turn (180 degrees), so that the fork of the blades catches the string and the string wraps a bit around each blade. in this move, you're going to do with your legs what i just described with the scissors; and then you're going to put your legs together, pike, and turn your top hip strongly into the fabric (the "hip-key" part).

hang free from fabric. while still hanging, turn rear end towards fabric, straddle legs wide, let fabric fall between straddled legs, and windmill legs upwards and over, catching the tail as high in your crotch as possible. bring legs together, pike, and turn hips strongly into the fabric.

strive to raise your hips as high as possible while windmilling the legs; this will help the fabric to settle high in your crotch.

variations. the fabric is locked by some combination of friction against a fold (where the silk that lies over the top leg/hip gets pressed into the pole), tension from rotating the hips, and pressure from the top leg against the pole. changes in leg position can change which of these is emphasized, and give different shapes in the air.
uses/builds on: invert (raising hips above torso while hanging-- though this move only passes briefly through that position instead of staying inverted).