Depending on the guy, friendship may not be possible no matter what you do. In any event, you have to be firm, but not cruel. Simply explain that you are not interested in them in that way, but that you might want to just be friends.
Just say a sweet LIE
with a smile on the face & say that you are extremely busy with your family on that day or you have to go out of the city due to some urgent work & maybe some other time you can go out with him.
Tell them the truth. Tell them that you want to pass right now and that a good friendship is better between the two of you. If they can't accept no as a response then you'll know that they are not even worth to be your friend.
