Kimbo Slice died Monday in a Florida hospital. The MMA fighter was 42 years old.A heart attack is believed to be the cause, according to a source close to his family. The CEO of Bellator MMA praised the fighter “Kimbo was a charismatic, larger-than-life personality that transcended the sport. Outside of the cage he was a friendly, gentle giant and a devoted family man.”Kimbo was scheduled for the headline fight next month at Bellator 158 in London. Before he entered professional fights, he became FAMOUS from his YouTube backyard brawls.He worked his first jobs as a nightclub bouncer and bodyguard to porn stars.