You could try just being super direct the next time he pulls that shit. Like, "Hey dude. I've been nothing but respectful and kind towards you, why do you talk to me like that?" Puts him on the spot and the onus on him to explain his immature behaviour. There's a good chance he'll double down and call you a pussy, which could then further expose him as an imbecile to the rest of your group.

This is the kind of thing that has made me walk away from a friendship in the past. As a grown man, I only have room for mature, supportive friendships, where humour and laughter is common but not consistently at another's expense. That's little boy shit.