Should I flirt back with this guy?

So I kinda like this guy and I really think he likes me too. He okay fights with me and talks to me and my friends. I've even begun to kind of like him back. He's a true intellectual, one of the smartest people I've ever met. The only one who can beat me in a debate. The only problem is... He's pretty much an outcast at my school. He dresses strangely, kind of looks like a hobo, talks about drugs (even though the doesn't do them) and gets in trouble a lot. My friends think he's a WEIRDO. They all hate him but admit he is very funny. Should I flirt back? Even if my friends disapprove? My friends are pretty important... But I like him.