Well I guess I can share a good but bizarre one.
Caveat: This is well before I met my wife and cleaned up my life. I don't live like this or condone it anymore. No one night stand or random women could ever understand what pleases me or satisfies me sexually the way my wife does. You can learn a lot about a person in 12 years of sex and good communication (seriously, if you're in a relationship and not talking about your sex life and what you do and don't like sexually, change that, it will do wonders for your relationship health).
On to the story:
I currently had an apartment with a girl, we served together in the military at the time (it was 2002, I was 20). She was gay, I knew she was gay and frankly wasn't attracted to her (don't get me wrong, she was decent looking but just not my thing). There was a very "bro" like relationship between us, she had no problem with my using the shower while she was in the bathroom getting ready, had seen me naked and vice versa and nothing ever happened between us. We had a common interest at the time, women, and that was enough to bond over that we didn't have any sexual tension between us. I could fart in front of her and not feel self conscious if that is any indication of the way things were.
She started dating this girl that was just... gorgeous. I had to physically work not to stare at her or make it awkward when she was around. One Saturday morning after a crazy party we threw the night before, I get up (it was probably more like afternoon) and take a shower and I am getting dressed when my roommate walks in. She tells me she needs a favor, I thought maybe she needed a ride, needed drop her car off to get oil changed or something. So I am like "Sure, what's up?", then I was completely thrown off when she told me she needed me to have sex with her girlfriend. My immediate response is "What do you mean?". So she proceeds to explain to me what every once in a while, she just wants a real guy, but doesn't want a relationship with one because they suck. I agreed, because frankly I was a POS of a guy at the time and could understand why women would not want anything more than sex with me (I was a good looking guy in incredible shape, but I was a dick, seriously). So she figured I was up to the task of sex without emotional attachment.
So the part that was really awkward, was that she pretty much instructed me on everything her girlfriend likes, WHILE I was having sex with her... though I learned a whole lot of the female anatomy it was more like being a part of a science experiment or instruction then normal sex. There was a ton of pressure to perform adequately as I was asked to please her enough that she wouldn't need a guy for a while. Apparently I did my job sufficiently and after she had a few orgasms I was asked to leave even though I had not finished yet myself.
So I was back in my room laying in bed trying to figure out what the heck just happened and my roommate comes in and thanks me. "Hey thanks for that, you did great, I knew you were well equipped but didn't know you would be such a good lover for her. I will be sure to recommend you to my other friends." She then walked over, hop on my bed, gave me the best blowjob I have ever received in my life, swallowed and walked out (up to that time in my life at least).
We never really talked about it again and things went back to complete normal except in that she would tell all her straight friends that I was a great lover, and set me up with at least 4 or 5 girls that summer with the complete expectation that I was only there for sex.
In the end, was a pretty good deal for me. Not so much for her girlfriend who could never be normal around me again. I think it eventually led to them breaking up because her GF was so weird around me and we were such good friends.
