I had sex with a straight friend once, a long time back. It was funny - I learned later that basically he figured he'd done everything with girls (and I'd heard stories, as he'd dated some mutual friends!), and figured he wanted to try a guy.
So, he went through this amazingly complicated setup - I was visiting another friend in Tokyo (where he lives (though he's white/American)), and after a party he was like 'let's go drink more', but all the bars were closed. Then, he was like, 'let's get drinks at my place.' Trains were shut, and we'd taken a cab across town from where I was staying ... by this point I'd figured things out but made him keep working because it was adorable. Long story short, we ended up in the only motel we could find that would accept two guys together (Japan was still very anti-gay at the time), had pretty great sex, and are still friends.
His now wife is hilarious and I suspect kinky as hell.