How do I get rid of a pesky house guest?

An old friend I went to school with is moving to my city and recently emailed to ask if he could crash on my sofa for 'a couple of nights' when he first arrived. As my flatmate was going to be away at this time, I said yes. Upon arrival he put me on the spot and asked to stay for two weeks (duration of time flatmate is away for). foolishly, I said 'okay' because he was begging. He has since been remarkably unhelpful, (eg. has washed the dishes once this entire time, does not cook) He is kind of like the comic book store guy from the simpsons and sits on the sofa blasting the TV all the time. Two weeks is up but he has indicated he intends to stay! Even when my flatmate is back and there will be no room for him. I told him it will be too crowded here and that I can recommend backpackers, but he didn't say anything. Then I thought -because I know he is on a budget- perhaps I am being really unreasonable and mean. But I don't see how you can move to a new city with no money? I feel like I have been kind to him, but now he is driving me crazy. I am afraid my boyfriend and flatmate will think I'm very impolite if I kick him out, along with all our clmates from school, who, with the advent of facebook will quickly find out I gave him the boot. I don't want to force him onto the streets, but this guy is not even someone who has been in touch with me recently (until now). How can I get him to leave, without making things awful between us?