Guys that smoke shouldn't be asking you to do smoke with them. If he is, he obviously doesn't want the best for you. Don't get me wrong, I'm a teenaged girl too, and a bunch of my guy friends smoke and sh*t like that, and i know that at least a few of them have liked me before but not once have they ever asked me to do it with them. Its not very cute to smoke, as a girl, or a guy as i think. If you like him enough and he likes you enough, it should be normal enough for you to say "eh, id rather not. Lets just chill at my house instead :] " or something like that.. Don't smoke, its not gonna make him like you more or less. Trust me, I'm a teenager too and i have friends that have been through simliar situations. Best of luck with this guy, hopefully he likes you back! Good luck to the both of you. :]