Respect guys. Don't tell them they're stupid. If you don't like a guy just let him know about it in a nice way, such as "I think our relationship can't go any further" or "I'm sorry, there's no way for us to be together" or make up another sentence that works for you better. Just be polite and respectful. Guys like when girls respect them ;) If you like a guy just come up and say "Hi" - you know men can be shy too! Guys may think you're already engaged, or that he's not your type... Eh... I don't know. Just respect each other.
Don't read it - it's just a small piece of advice to boys and girls. Seeing society split and broken down into many different subgroups isn't nice, you know. Let's make society better together ;) It's possible, because if you want to change the world change yourself.