It is just for a laugh and for pranks and these people take it to another level. If it was malicious from Bear, he'd personally attack them back (and in the first place when he messes with people). It's LITERALLY just child-like banter & random noises from him all the time.
The only legitimate "insult" I can think that he's made is calling James a "bald eagle"... he's really just playing around almost all the time and people let it get under their skin SO BADLY even after they know that's just his shtick.
Meanwhile, he does a prank and Renee is calling him 12 names in the same sentence and threatening to take his head off lmfao...