Sometimes when you see someone doing something wrong, something really bad for them and you want to keep them from harm by letting them know how awful it is the worst thing you can do is rant and rave and bring out the obvious about it. Sometimes it takes a little psycology. They do things to look Cool. To be Different. To Stand Out In The Crowd. To be considered Tough, or Cool or even Dangerous. Often if they find out they're just making themselves look stupid and the people they are trying to impress are actually laughing at them they'll stop on their own.