Parents need to get out of the way of their own egos and roll with the fashion fads that their kids adopt. Part of the reason why he's dressing very differently from how you dress (or want him to dress) is his need to further separate from you at many levels. He'll soon be on his own in the world and he's asserting his own need to carve out an independent identity from his parents, an identity that he chooses.
Please remember when you were his age and what the styles were then as a coping mechanism for your distress. Long after the pants narrow and the piercings become fewer or disappear, he will remember that you did not shame him because he would not dress as you wanted. How he dresses is not worth fighting about. Learn to laugh and, above all, cherish this fine boy.