First, take two small towels and fold them into squares. Place on a slick surface like a wooden floor. Step on them with the balls of your feet.
Place your hands on the ground and drive your right leg back. Quickly switch so your right leg is in front and your left leg is back (like you are doing mountain climbers).
For even more inner-thigh targeting, do this variation:
In a low squat position on the towels, turn your right knee out so it is pointing in a diagonal.
Drive your left knee back toward a corner so it is diagonal from your right knee.