First off id like to tell you why its called a coindrop

(for those of you who know just skip this :P)
Ever dropped a coin?? (the answer to this is yes...) Drop another one. Look at how it falls and stops. It circles around a few times before falling flat, this kills all falling friction from the fall.
The same thing is what happens with a coin drop, you roll onto your shoulder like in mills and kill all the falling action.
Now to proceed.
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try this first on a mat, grass, cardboard, rug, or any other soft thing. First time i hit so hard i wanted to die :P
After you get better at it try it on hardwood or any hard/flat/*shiny* surface.
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Ok first:
What you want to do is get into normal standing position with your legs about double shoulder width. Less or more is fine, but around here. Make it comfortable.
Second:
Dip your shoulder down,
To do this swing your hand (fist it, might help) around a fake barrel attached to your chest.
Third:
Now drip down with your shoulder, and with the leg thats on the same side as your shoulder swing AROUND the back of your body. At the same time kick off with the foot of your other side and bring it up.
notes: You should be rolling on your upper back/shoulder.
I wrote the sides "This side, that side, and whatnot" on purpose so this guide can be used for both ccw, and cw.
Tips:
Remember to keep your legs straight and locked at all times. Also keep them v'ed.
Try right before your dripping your shoulder to step back a little (like a flar but not so much) with that sides leg.
Try going into various moves from this. Backspin, Windmills, Try popping back onto your other side and into footwork.
Lots of cool stuff can be done with this.
If you hurt yourself trying this just rest a little while, maybe even a few days and try again. Everything can be done.
If you have any questions just ask.
Vid:
http://www.bboy.org/gallery/showphot...cat=998&page=1
(i couldnt save a vid clip for it for some reason. So here one from the site. Props to azn.)
Note: This was taken from breakers video. hes not the best teacher, but hes a fairly good bboy.