Most Helpful Guy
Life favors those who are bold enough to try. Just ask the guy out. If his response is "I have a girlfriend," or something other than yes, don't let it show that it bothers you. Only the lowest scum would intentionally hurt someone that just stroked their ego by asking them out. That said, you'll likely catch him off guard, so whatever comes out initially will probably be less than tactful in any case. It should quickly be followed up with some sort of explanation though. And if he is scum then you're better off with him having said no.