I've said it before and I'll say it again. There is nothing wrong with peer pressure. Everybody belongs to some social group and adopts many of the societal norms they find their peers following. For example, why do so many teenagers skateboard, dye their hair, or use the latest slang words? Because they enjoy doing those activities with their friends and they consciously chose to do it out of their own will. It's not like people are being forced into following societal norms; it's just what humans tend to do because we are social creatures who like to have a sense of belonging. Smoking pot is no different. If someone consciously chooses to smoke pot because his friends all seem to be having a good time with it, what is wrong with that? He's not harming anyone else, and nobody is going to beat him up if he refuses (if someone is threatening to beat him up, then the ethical issue is not peer pressure but violent threats, which is a different ballpark). Everyone should be able to do as they please so long as nobody else gets hurt in the process, no matter what their motives are in doing the activity they have chosen to do.