Start in a push up position. Keeping your feet in one place, walk your hands about 190 degrees, just like the hand of a clock (your feet being in the centre of the clock and your hands the extremity of the clock hand). From there, walk the hands back to the original position.
Keep the core tight and avoid rocking the hips. These can also be done with the feet up on a step, bench or tyre to increase the difficulty.
Sometimes referred to as Around The Worlds.