Want to start off by saying the story is 100% true, so if knowing a story is true turns you on even more, I wanted to point that out...
This is how my girlfriend at the time 'forced me' to sell my used underwear to her male coworker which then led me to keep going because I oddly enjoyed it...
I was 32 at the time (35 now). I keep my body in great shape from working out for over 15 years. When I was younger, injured to powerlift and as I got older, due to injuries, I started shifting into body building. As I write this, I am 225lbs, and around 10% BF and my background is Italian and Irish. I have a 6.5-inch cock, so nothing massive but it is a nice cock I have been told.
I have always considered myself straight but also not shy about being naked in front of other men (I guess from sports in college and 3sums growing up).
It all started when we had one of my girlfriends' coworkers over with his boyfriend. It started as a regular dinner but after a few drinks and shots the conversations started to get little sexual in nature. I didn't mind it because they were both gay so talking about how good my girlfriend sucked dick was turning me on. My girlfriend also kept talking about how much I worked out and how she found it so hot that she gets to be fucked by a Muscle Stud. Of course, I enjoyed hearing this so I just enjoyed the time.
But this is where things started heating up a little. John and Tom (my Girlfriends coworkers) kept complimenting as well and my girlfriend was getting turned on by it. Then John jokingly told Tom he wouldn't mind seeing what was under my shirt. I laughed it off and told them they were crazy but My girlfriend kept telling me I should but I just kept brushing it off.
She poured another round and we all kept talking having fun. I was feeling nice at this point and my girlfriend asked if anyone wanted dessert. John told her "If dessert was seeing your boyfriends' abs, then of course". He looked at Tom who quickly agreed. I just told jokingly them that the show would cost too much. But my girlfriend came over and said if I agreed to show them my abs, she gives me the best blowjob of my life later. Now I know she sucks amazing cock to begin with, but hearing her say that in front of them did make me horny.
So, I stood up and lifted my shirt over my head to show off my body as they kept begging for as my girlfriend cheered me on. After it was fully off, John and Tom both looked at my Girlfriend and John told her she wasn't lying. Which was kind of hot hearing someone else compliment my body.
I was about to put my shirt back on and my girlfriend stopped me saying the deal was to keep it off. I told her we never agreed to that and she just said it was implied but wanting my blowjob later I said fine.
The drinks kept flowing and seemed dessert wasn't going to be served yet as everyone was having a good time and dessert usually means the night is ending.
I kept noticing that both John and Tom were staring at me and my girlfriend caught it too and told them they could keep looking. I mentioned how it was unfair how I was shirtless and that she should take hers off too (not caring because obviously they were 100% gay) but I wanted something to look at myself. Without hesitation she took her top off exposing her perfect tits in her bra and just walked over to the counter to get the bottle of whiskey we have been drinking. At this point I am definitely drunk and feeling really nice. Horny too looking at my girlfriends' tits thinking about the blowjob I am going to get.
Then my girlfriend asked John what he was into and who the top and bottom was. John laughed and said he was the top and Tom was the bottom most times. Tom chimed in and said sometimes he will Top but is more of a bottom.
And this is where things really heated up.
Tom then mentioned that they both have plenty of kinks but there's one that they both love and is how they met. Now my girlfriend is an extra kinky woman, toys, bandage, roleplays, etc. so when Tom said this she basically stopped and was waiting for Tom to tell her.
He didn't tell her right away and she said "oh know I need to know, like bandage, roleplays and stuff like that?".
Tom looked at John and laughed a little and told her it definitely wasn't a normal everyday kink. My girlfriend basically begged to hear what it was.
Tom told her not to judge him and my wife laughed and told him she never could since she was probably just as kinky.