Call of Duty Black Ops Nuketown Musical Easter Egg

On Nuketown There is a Easter egg where if you shoot all of the mannequins in the head  in 15 seconds from the beginning

A rolling stones song will start to play.

Since you only have 15 seconds it is implied that you need a bunch of good players to do this easter egg.

Well shooting all of the mannequins 15 seconds is hard enough but to headshot is even harder.

Well I can really show you an easy technique for this because the mannequins spawn in different spots.

So i hope that you can shoot them all in the head so the song will play.