you say "wanna go toke up?"

and they either say

a.) "no way, i don't want to ruin my life, become an idiot, get lung cancer, and/or get arrested"

or

b.) "yeah"

...or

c.) "yah because i smoke all the time and i'm a huge stoner, dude, totally i'd bake with you but i can't now because i don't feel good." and that same guy tells everyone that you two baked together, you then know he's one of those poser-stoner-does-it-to-be-cool-fags and you just beat the shit out of him and walk away