definitely Dan!
I remember one time sitting with a guy giving each other massages in a chillout area... somehow we got on to the topic of sexuality and I found out he was gay.
I was damn horny and definitely interested in this guy and we were both having a nice time with him sitting right up against me and me massaging him. But as much as I would have wanted to do more, I was really conscious of my "super-straight"(tm) friends and that they were looking my way and at the time I thought perhaps they were wondering if they thought I was being a little to friendly. In hindsight they were all as fucked as I was so there was probably no such thoughts going on, but it played on my mind at the time.
Would have been happy to go somewhere private and explore with this person, but it was not meant to be.
I think I should explain why I was worried about what others would think. I am basically straight, but have always been curious/interested (sexually) in sex with a guy but rarely had the situation present itself where I was attracted to a guy enough, etc. Given that my curiosity and sexual desire is personal and private I was not interested in changing "who I was" in people's eyes. I have friends who would be totally at ease with this, but I know that many would see it differently. Not actually being interested in guys romantically I figure that I would rather keep things this way even if it means never exploring this part of me.
I have also had some bad experiences as a kid around this that definitely has caused me to "chicken out" despite really wanting to go further. Including one that is pretty funny/freaky where the story starts as me as a teenager and ends not that long ago. I think I should post this in another thread just to see if people have any similar fucked up stories!
Compare this with my girlfriend and my ex housemate. We were out one night and my housemate was in to kissing girls for fun and pleasure when off her tits... so she got my gf into this and it was enjoyed by all, including many onlookers. I can imagine that the vibe would have been different if it had been 2 guys deciding to do this.