A little more information would be helpful. Is this a friend? Someone you know well? Or someone that you just pass in the hallway at school and he makes you go all "butterflies in the stomach"?

Bring up gayness in a conversation, like a gay celebrity, and then a topic like gay marriage, and then just straight out ask. That way, it's not nearly as forward, and it softens the blow of asking.

depends on how close you are with him.. please elaborate on details