Mixed martial arts is one of the most brutal, yet fun to watch sports that we have in the US today. Basically it's boxing with smaller, open-fingered gloves, where you can also wrestle and kick one another in the face. Now take that times ten and you have group MMA fighting... 

Although there are also 5 referees to help control the action, it still seems like having ten guys inside a cage fighting compared to just two, could get a little more brutal. It's about the closest thing you will find to a legalized street fight.

At this point I know of none of this going on in the US, so for now enjoy watching European dudes beat the ever loving sh** out of one another...