Good grades=better job
Better job=more money
Better job + more money = better life + more opportunity for anything. You could do anything you wanted to.
You need to think about the future an even if you don't care, one day you will care about your grades. Your transcript follows you forever. It's like a creepy stalker that will never go away. Now is the deciding factor for the rest of your life. I know this doesn't sound very Christian but find the inspiration in yourself. You do good now you don't have to work as hard later.
In other words:
Your gonna get a super hot wife(s) and do what you want with out getting in trouble.
Your signature has been removed due to excessive homosexuality.