After watching Gran Torino which was a terrific movie, I wondered how the term zipper-head came to be. I found this explanation on the urbandictionary.com website.

Used during Vietnam, Charlie was coined zipperheads because of the way a head looked after it had been hit with a high powered automatic weapon. The the typical rising machine gun would cause a face wound that looked like an open zipper on the face of some one from the viet kong.

That gook looks like a Zipper Head because of the machiene gun fire.

Use a bar of soap. Rub it on both sides of the zipper, then work the head up and down. You might need to re-soap the zipper once or twice more and work the head up and down a few times to ensure the soap gets into the grooves. Works for me ;-) More information Try rubbing a pencil on it - graphite is a terriffic lubricant.

He sure does.... it's half zipped, half unzipped

during war so many japanese bodies were piled up in the roads. when the tanks came through and crushed the heads it left a zipper pattern on the crushed skulls.