Dollar Bill Technique

I just saw of video that demonstrated this technique of playing guitar. It gives an interesting percussive effect, like a snare drum, it was said. Johnny Cash used this technique, so I went over to look for one of his videos on YouTube and found this one. If you look carefully, you will see. I looked at the drummer, and it looked as if he wasn't playing, yet it sounded like there was somebody playing drums. Hard to say if the guitar was making that sound. Anyway, here it is.