I can pop my hips two ways.
The first, I think more common, is by crossing my feet, then pushing the crossed feet against each other.
The second way is harder to describe and cracks a totally different part of my hip. I do it by twisting my upper body against my hip, then bending my upper body downwards a little bit. It twists something out of alignment in my upper thigh, and can be painful, and isn't the most satisfying crack, so I don't do it often.