The Guy Who Lives In My Back Yard

There is a man renting the apartment that is in the back yard of my house. Well I've lived in this house for about five months now and I still don't know his name cuz i would only see him occassionally. So i call him the guy who lives in my back yard (but not to his face). About two weeks ago he knocked on my front door with a couple beers, so i invited him in. HUGE MISTAKE. He then made a habit out of coming over every night after this. And it turns out this guy is a drunk. And he is one of those drunks that doesn't even try to speak, he just uses drunk sign language. One night he came over and offered me beer (which i decline every time now). He sat on my chair and continually spit on my floor. He would try to talk to me but was drunk beyond speech. I guess this spitting thing is acceptable here cuz he is not the first person to spit on my floor. Anyway a few days after this he knocks on my front door cuz he is too drunk to figure out which of his keys unlocks the gate to the back yard. The next day he comes over (oblivious that he'd made a fool of himself the night before), and starts the spitting thing again. Eventually his spit flies in the air and lands on my computer, this crossed the line in my book. I told him that it was rude and i wished he would stop. He immediately got up and left and hasn't been over since. I guess i offended him somehow, but i don't really care cuz i've gotten rid of him for now. But i don't expect it to last cuz he lives in my back yard which makes him a little difficult to avoid.