How can I be a confident guy in this situation in high school?

If you dont want them to think you are gay, go for an ugly girl, ask her out, she is bound to say yes if she is ugly enough. bang her, tell everyone, even take a few pics of her naked and then you will be the man and everyone will think you are a funny cool guy for doing that to an ugly fat chick just to 'embarrass' her and everyone will know you're not gay. simple!!!