A straight edge person, is one who woke up one morning when one was around the age of 14 and one realized, "Wait, I haven't done any drugs yet, all of my friends have, I need to come up with an excuse for why I'm not cool. I know, I'll tell everyone I'm straight edge!"
One then lives one's life until the age of 23 being straight edge. Get's "xxx" tattooed on one's arm, never gets laid. Upon turning the age of 24, has a beer, regrets the tattoo, and realizes it's too late to ever have sex because one is a homo.
See Homo Thug
Person 1: "Hey man... you know when you're tripping and-"
Cut off by Person 2: "No way dude, I'm straight edge."
Person 1: "Oh, so do you like butt sex?"
Person 2: "No, I'm straight edge."
Person 1: "You're gay."