Yeah, marijuana and alcohol are so available, especially in social settings.
I know it's really hard to say no sometimes because you'll look like a "party pooper."
But I don't think you should feel pressure to do them, especially when you don't want to.
If you don't want to draw attention to yourself... Can you just fake it?
Pretend you're smoking but don't inhale & as long as you're holding a solo cup nobody is going to bother you - just fill it up with pop