I'm not going to lend a friend a boardgame that he wants to play tonight.
Is there a reason behind you not wanting to lend it to him?
I'm just too busy with my studies to deal with him.
While it is good that you are prioritizing your schoolwork, it isn't a valid reason to not lend out something that your friend needs. Friends try to help each other and you are not being a good friend by not lending out your board game without a good reason. Have your friend pick up the board game at your place so that you can give it to him without spending much time.
I don't care. I won't lend it out. I'm too busy.
I get that you are busy and I commend you for paying attention to your studies, but it will only take a minute to share. It's the kind thing to do.