My coworker which shows clear signs that he likes me suddenly started calling me bro at work, why?

He called me bro right after our other coworker (guy) remarked that he always treats me nice, he said bro in a aggressive kinda way while we were discussing something. This coworker (guy) remarked the idea stating that he only is kind to me but not to other coworkers in works
My coworker which shows clear signs that he likes me suddenly started calling me bro at work, why?
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