Clearly you had already caused problems, we're a low-profile server-goer an the host didn't want to up with your stuff. On the one hand, a host SHOULDN'T ban for no reason. On the other hand, it's his 'party', and I'd you violate his rules, be they unwritten or otherwise, he can kick you out without warning.
In layman's terms, you were an idiot and got banned for it. Saying stuff like /afk wanking is funny when the server is either your own, or your with friends. If these are people you just met, that's like walking out into public, getting on a bus, and someone asks you if they can sit next you...
"HOLD ON GOTTA WANK FOR A BIT K"
They walk away, then you shout back "I was only kidding!"
Try harder next time.