I have a question about gta?

I was playing yesterday and entered a bomb the base lobby because i never played that. so there are two people in there not counting me we start and i see two vehicles i get in on and on guy throws a grenade at our vehicles then he keep throwing grenades at us trying to kill us so they try to kick eachother and I say in to my mic "you shouldnt be a ***" and we kick him. later he sends me text messages calling me a ******* lifeless noob. can someone explain this