This is a variation of the marichyasana ("ray of light") yoga pose, which massages the abdominal organs, stretches the shoulders and strengthens the spine. (Not recommended for those with spinal injuries, or high or low blood pressure.)
Sit on the floor or yoga mat with your legs extended in front of you. Bend your knees (Indian-style) with both shins inward and left leg in front. Keeping your left leg bent, reposition the leg so that the left foot is flat on the floor.