TweetPipers are skinny guys that stand in front of the mirror and lift their shirts up a little and check out their abs in the mirror. Also, a piper can be a skinny guy that wears a t-shirt and rolls up his sleeve a bit to expose his 11 inch arm. I workout at a college weightroom and this college (Case Western Reserve University) is known for smart nerds, so that is all I see in the weightroom.