You can't "turn" gay or straight or bi, or any of it. However, I do not believe men that say no. They'd gladly all bang eachother, lmfao.
They're only saying no because they don't want to be seen as queer, even online, because they are that insecure. If everybody else was banging eachother, they wouldn't care because it'd hardly be possible for them to point the finger.