weird biting ritual

Roxy does this thing to men only.. say he comes into the room and a male friend is sitting in a chair not moving at all. Roxy will walk around the chair, head bonk the guys leg, then start licking it (if bare). After about 5 licks, he will attack--bitting, clawing, etc, like he's trying to kill the guy's leg (sometimes he'll do it real rough but usually just in a slightly more menacing way than when playing). It is really strange. He also does this to arms, backs, and stuff, mainly to guys, but one in a while he'll try for me but I know his tricks so I head him off before he gets mean. I'm not sure what sort of aggression this is, but if I get him to stop he's usually just perfectly normal afterwards, no hostility or anything. Any ideas?

What is Roxy's history? Has he always been your cat or is he a rescue? Has he ever to your knowledge been abused before? Something in his history may explain his behaviour.

It could be that he's getting overexcited from head bonks and licking resulting in him biting. That could maybe explain why he does it to you too but you notice the signals before he bites and head it off.

Perhaps there could be a scent that Roxy is picking up that he perceives to be a threat to his territory and feels that a head rub isn't enough to mark his scent and needs to bite.

I don't know what else to add. I hope some of what I have said has helped. And maybe someone else can suggest other possible reasons.

Maybe Roxy is responding to movement in addition to any scent. If he thinks the leg is alive, the licking could be a test, followed by the the attack (or kill/attempt to kill) of his "prey." Does Roxy have plenty of toys to practice his hunting skills on?

Maybe Roxy feels challenged by men coming into his territory.

With you, it might just be play.

Just make sure the guys are forewarned.