This story will seem lame by comparison to all these others, since it didn't happen to me. I've let closeted older married guys blow me a couple of times, but this thread asked about blowing straight guys, which I've never done.
I got turned on this weekend hearing about something. I was hanging out with some people here in NYC and one of the girls present mentioned being in a sauna. I said something like, "Oh, right, I guess women don't just go to saunas for the sake of having sex with each other." And the girl said, "Funny you should mention that..." and proceeded to tell a little story.
A straight guy she knows was in a sauna not long ago and accepted 200 bucks to let a guy blow him. The guy doesn't know she knows about it. He told a mutual friend and the mutual friend told her. Apparently the guy's kinda messed up over it and is having a hard time with the memory. Probably not wanting to offend me as the gay guy present, she said she was sure it was the fact that he prostituted himself, rather than that he fooled around with a guy, that was so disturbing to him. I said it was probably a mixture of the two and she admitted that, yes, it probably was. Apparently this straight guy's always been a troubled soul who lost his brother in a motorcycle accident and doesn't always make choices that will lead to his happiness. I felt sad at the prospect of a straight guy prostituting himself to a gay guy and then feeling dirty and disturbed over it. But I was also REALLY turned on.
I was dying to pump her for details if she had any. What gym was it? How did it come about? What was the guy who gave the blowjob like? Could I have a description of her friend, or his name so I could google him? But I barely know this girl and a couple of the other people present and so didn't want to come off pervy and weird, which wouldn't have been a scruple for me if I had been with only good friends - who already know I'm pervy and weird

I only asked her if her friend was hot, and she said yes he was a good-looking guy. I assume that the guy who gave the bj started off offering it for free and then the "bidding" went up to 200, so her friend is probably pretty desirable. That night, I went on the girl's Facebook page and scanned the pics of her male friends and wondered if one of these was the guy.
While the bathhouse culture in New York City was decimated by crackdowns at the height of the AIDS crisis, hookups at gym saunas around the city are apparently pretty epidemic, but I haven't belonged to a gym with a sauna since moving to the city and, being a poor grad student, can't afford to change gyms.
I've never sucked off a straight guy. The couple of times I've been around guys who made me think it was an option (i.e. they drunkenly admitted to me they'd thought about fooling around with a guy), we had friends on hand and it didn't seem possible to make a move.
As an aside, contributing to my horniness when I heard the story was the fact that we were sitting in Central Park. Has anyone ever been in Central Park on a weekend in summer? You couldn't throw a stone without hitting a shirtless male runner. There are legions of them everywhere you look, and it makes for spectacular viewing.