I have never done anything sexual with another guy but that doesn't mean it will never happen. I consider myself straight (for whatever that term is worth) but have some same sex attraction. I'm not sure if it is even enough to consider myself "bi". If there is a really good looking guy with a hot body around, I definately notice him. But maybe this is something lots of "straight" guys notice but would never admit to. I don't know. It's just something guys don't talk about, but I have a feeling I am not alone.
The vast majority of my sexual fantasies involve women, but I sometimes fantasize about men. My male fantasies almost always revolve around sucking cock. I am mostly interested in exploring another guy's cock, stroking him and then going down and sucking him off. I really like my own cock and actually kind of get turned on by it, I think that's why I have somewhat of an interest in cocks in general.
I'm not sure if I would ever actively look for a hookup with a guy, but if I found myself in a situation where another hot guy was interested in fooling around, I'm pretty sure I'd go for it.