You do Muay Thai, correct?
When I was in middle school and high school, I used to kickbox, box, and spar a lot. My passion was Filipino/combative arts, but the school I was affiliated with was a Kickboxing school. The owner was a World Champ back in the late 70's.
Anyways, there was no "fight club," but there were a fair amount of kids who wanted to fight me because I was in martial arts. So, I would tell them that although I liked to study martial arts, I didn't like violence. I would rather be friends with everyone instead of fighting. I would also say that "Hey, really...I don't think I'm that tough." However, I would also say that if anyone really wants to fight me that bad, then here is where my martial arts school is at. We can sign waivers, put the gloves on, set the rules any way you'd like, and go at it. I'll have my instructor referee so it doesn't get out of hand. Then afterwords, we can still be friends.
I only had a couple of people show up, but it was to first check the school out. When they saw me teaching other people who were adults, and when they saw me in the ring, they changed their minds about fighting me. From 10th grade on I never had any problems. People knew I was nice and that I would never fight unless I had to. They also knew not to challange me. This due to my demeener, primarily. Secondarily, it was also because a few of the drug dealer seniors tried to jump me in school when I was in the 9th grade. These "tough guys" ended up on the floor in tears; and luckily the kids parents where smart enough to drop the law suit. People also knew not to push me to far after that.
The moral is....don't ever go to someone elses "turf" for a fight (I'm excluding competition, and talking about "real fighting"). You will be at the mercy of their rules, their crowd, and you will have to play their game. You will be putting yourself in a situation of which you will have no control over, meaning that no matter how tough you are, the odds will be extremely against you. If something happends spontaniously, handle it accordingly, and remember that self defense isn't just "beating" someone in a fight, but that it is doing anything you can to get out of the situation (whether that means running, getting the authorities, etc.). You don't want to foolishly endanger your life. And third, if they are instisting on fighting you, make them do it on your terms. If you are at a Muay Thai school and currently training for the ring, then this shouldn't be a problem.
Good luck, and be wiser them your peers.
:ultracool