
The more you rage at them the more determined they will be to carry on. I've found the best way to deal with teenagers and this sort of thing is to calmly tell them that you know they're doing it, that you think it's a very stupid thing to do (but
don't call
them stupid - big difference) and that you don't want it done in your house.
Say what a shame it is they feel they have to 'go along with the crowd' like this, that you'd hoped they had more self-confidence. When you can smell smoke on them, say "Pooh, you stink! Go and put your clothes in the wash and have a shower". And say how proud of themselves they will be able to feel when they stop.