I can imagine Clark being too much of a boy scout to try weed. “Sorry, it looks like a lot of fun, but I promised Ma I wouldn’t. I can still hang, if you’d like. I’ve got snacks.”
Definitely the kinda guy who notices someone taking an illegal drug, then spends the night checking up on them to make sure they’re okay. He asks if there’s anyone they came with and offers to drive them home, since he’s only been drinking diet coke the entire night. Then he texts them in the morning, just to be safe.



He is the cool Superman, but he’s still Clark Kent, the boyscout.
Just look at his attitude towards swearing. He never condemns anyone’s swearing (except in cut dialogue about saying “pussy” in front of children), but his swears of choice are “golly” and “what the hey”. He will quote people using “supershit”, but makes it clear he doesn’t approve of it.
I do believe that the Kents would teach him about safe drug use, since they grew up in the 70s, but only so he’ll be safe. Then he uses what they taught him to make sure everyone else is safe, not so he can do it himself.