A "Hip key" on the aerial silk is a stock move utilized by virtually every aerial silks artist. The move is utilized as a beautiful pose within itself (you can SPIN by helicoptering the tail of the silk!) as well as to get into many other moves up in the air.
Have you ever been to the circus and seen the girls sitting high up in the air waving at you? Perhaps you wondered to yourself, "How in the world are they sitting on that fabric??"....well, it starts with a hip key :)
Mastering the Hip Key is kind of like riding a bike; you have to try and try and try again to not fall out! BUT once you get it, you've got it for good.
Here's a tutorial on how to do a hip key from the ground. (When first learning a move, always learn it low to the ground.) It is demonstrated on the right side, but can easily be reversed to the left side. Once you've mastered this move from the ground, try to climb a few times and do it in the air.
Stay Fit and in Flight :)