Either bite the bullet or forget about it. However, if he really is homophobic, the only question is why? It's surprising how many homophobics there are which are themselves gay. They just don't want to admit it.
Has he had a girlfriend/boyfriend? If neirther, then the best course of action would be just to say how you feel.
Advice: as you said, you joke around. Try adding something like this into a joke. (Be warned; it can scare the life out of the recipitent. I used to have a gay friend, who apparently had feelings for me. Unfortunately, I was brought up to believe the negative load of lies (not my first choice of words, I just do my best not to swear) about gays etc. I still feel guilty about what I did.) The relevance of that story is-don't just accept a 'no' immediately at face value. It is never certain. Stay friends with him if he says no.
However, if he has had a girlfriend, then sorry, but give up. If he was close, he's probably straight. if they weren't, he's too homophobic to admit he's anything else. If you're wondering why i'm not saying he might be bisexual, it's because male bisexuals are incredibly rare by comparison to any other orientation.