This is a spinning drop from standing onto your back. You will see people do it both with hands and without as they start windmills. It takes its name from the breaker named Chino in the film "Beatstreet". You really need to have windmills down for this, or at least the first stage. It is assumed that you are spinning anti-clockwise.
1.Start from standing, legs twice shoulder width apart. Swing your left leg in front of your right.
2.At the same time keep your left arm high and start to reach down towards your right foot with your right.
3.As you do this, powerfully swing your left leg in a circular and upwards motion from the front, to behind your right leg. At the last minute give a little jump with your right leg.
If this is done correctly you should end up in some sort of 1 handed balance at about 45 degrees. This should feel similar to the start of a swipe or 1990. Anyway, repeat the process but this time, as you are in the air, bring you left arm (which was high) downwards and throw it under your body, tucking in your left shoulder.
At this point it will help to keep your legs apart and prepare for windmill mode. You should also push a little with your right hand.
hope this helped.
p:s heres a cool site for breakin' explanations. really cool, check it out.