With long enough arms, you can pull an item clear from your waistband, and push it sideways so that it is pointing either sideways/forward, next to your torso. Sideways seems easier, and you can see what you are aiming at. It isn't easy however but the whole situation is v unusual.
I once saw a prisoner who was slim and flexible pull his knees to his chest and bring his cuffed wrists past his feet to his front. He was not trying to escape. He was laughing at his prank on the arresting officer.