The fight was part of a Strike Box event, which was supposed to feature modified rules that were more like a kickboxing match than mixed martial arts. The problem, however, is that the local athletic commission never approved the modified rules, so when the fighters showed up they were told that in reality, the commission-approved referee would enforce standard MMA rules.
That's where it gets tricky. Thompson and Bosse supposedly made a gentlemen's agreement that they would use the modified rules, even though referee Yves Lavigne (well known to UFC fans) would treat it like an MMA fight. And then as soon as the fight started, Thompson decided to disregard the gentlemen's agreement. Here's how MMATraining.com describes it:
Thompson shot in on Bosse and took him to the ground. He then moved to side mount and starts raining down punches and elbows on Bosse. Eventually landing in full mount with more punches and elbows. Referee Yves Lavigne had no choice but to let the fight continue, since technically it was an MMA fight.The bout was ultimately ruled a no contest, which means Thompson and Bosse can treat it the way we'd all like to, by pretending it never happened.
The fans began booing, not realizing what was happening and eventually tossed beer cans into the cage as the fight played out. Then a few chairs were thrown into the ring as a near riot broke out. Referee Yves Lavigne was forced to call a stop to the action and finally had to throw Bosse out of the cage for tossing a beer can at Thompson.