Living with Clingy

I can deal with some weirdo hitting on me online and stalking my Twitter, FB, whatever.
But not this.

Why is the guy sleeping on our couch that has no job, no car, and no home trying to hit on me?

I can't pee. If I leave my room to go the bathroom, he tries to talk to me for ten minutes when I don't want to talk.
I can't cook. He'll come to the kitchen and try to talk to me about giving him food or hit on me.
I have to keep my door closed and locked so he doesn't see it open and try to come over. He does this alot. If my door is even cracked, he tries to find excuses to come to my room.

This is the worst.

I'm a prisoner in my own home.

Why?

I thought you're supposed to be able to relax in your home.