Well, if he's the type of dad who actually listens to you, you could just stop caring if he sees it. And if he does react unfavorably you could explain to him that you hear more swearing at school than you see in the game. Not to mention that in the game you don't actually have to hear it.
If he's NOT the type to listen to you, get a job or start doing something that makes you a bit more self sufficient. That usually makes them start paying more attention to what you say and/or think.