A guy asked me out, i rejected him, now...?

you say you wouldn't date him because you don't know him and you said you could be friends... hanging out is a part of friendship, and a big part of getting to know another person. If you don't like him after meeting him and getting to know him, you don't have to hang out again and you'll know exactly why you don't want to date him. Don't go into it expecting to dislike him though. You never know you might find a new friend or possibly a good boyfriend, you never know.