It really just depends on how you feel deep down.
[NOTE: I apologize to anyone I may or may not mislead, I have extreme anxiety/fear of being alone issues.]
Dates are supposed to be fun. If you feel that if you went out with him and didn't have a good time, you aren't obligated at all to say yes to a second date. Besides! If you just relax and get to know this boy, you may find out that you really could like him. If he tries something inappropriate or that you are not comfortable with, then you should politely ask him to stop, and if he persists, you could leave or simply pull out a cell phone and call your folks to let them know that you would like to be picked up. Parents are there to help you on dates, I personally feel that parents should prep their children before they are put out in social events without the guidance of their parents, but people these days don't realize that one of their main jobs as a parent is to guide their children down the right path.
Boys are forgiving most of the time, so don't worry if you make a blunder. Hell, they probably make some that we don't even notice.
I for one, whenever I leave for dates, am usually asked what I feel is okay and what is not okay. I generally will tell them that I will do almost anything within reason, and if I am uncomfortable with them, I will let them know. Some boys would take that as a ticket to easy sex, but I try to sort out mentally which boys would not feel that way.
It's also a good way to filter out men and see which ones are worthy of your time. I don't mean to say that you should act stuck up, but there are ways of turning down an invitation without being rude.
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If he continues to persist to ask you out, then you can notify a teacher or a parent and let them know that you are not feeling a-ok with his actions. If you tell him yourself and he thinks you are joking, then I would suggest that you immediately tell a trusted adult. You never know what could happen if things get out of hand.