Can I slap my friend?
Are you kidding? What made you want to slap them?
I want to slap him because I think he is being inconsiderate about me
I'm sorry he's being like that, but if you think he's being disrespectful to you, you should talk to him about it.  Responding to that sort of activity with violence is wrong, especially when it's a friend.  I'm sure this is all just a big misunderstanding!
I'm going to slap him and it's not a misunderstanding.
I know you feel hurt by his actions, but don't resort to violence because you are too smart and too kind to do that. You have always been the cool-headed type of guy, so slapping him goes outside of your character. Just do what you do best: communication, and resolve the issue with words.