It should go without saying, but if you ever feel the urge to talk trash about MMA fighters in the presence of a UFC heavyweight, don’t.

Derrick “The Black Beast” Lewis, a highly ranked UFC heavyweight, was at the gym on Wednesday when a boxer started talking trash about MMA fighters, according to ESPN MMA reporter Ariel Helwani.

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According to Lewis, the boxer said he would knock him out because he’s an MMA fighter.

That ill-advised decision resulted in Lewis getting in the ring with the boxer (not a professional, by the looks of it) and what resulted was a ferocious 1 minute annihilation that ended all debate.

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