the word staightedge is used to describe people who have made a life choice to refrain from drinking, drugs, smoking, and sex. there is nothing wrong with the people who have made this choice, and others should accept it, as well as they should accept others life choices.
kid 1: hey want to go to this party? there will be a keg.
Kid 2: no, i'm straightedge
Kid 1: ok, that's fine. i'll see you later.