Getting him to change might be impossible now. The kid is set in his ways. The first 10 years of ones life are crucial for learning and developing good behaviour.
My little brother grew up with TV in his face and always being spoiled. He thinks everything will go his way. He is now 11 and lacks on his school work. How can I get him to stop acting this way?
I'm doubting that you will have much influence on this problem unless your parents get on board so everyone is on the same page.
If you try to correct the behavior and little Johnny is still getting spoiled by your parents, whatever you're doing is being undermined.
You can try speaking (nicely) to mom and dad and get their viewpoint on why they are letting this poor behavior continue, but you need to do it in a non-judgmental way. No one likes to be told they're a bad parent, so if you go into the conversation with this intent, it will backfire.
You might respectfully disagree with their approach and suggest another way, but ultimately little Johnny will do whatever the heck he wants to do until mom and dad lay down the law.
You might check out John Rosemond (www.rosemond.com) and see if that resource proves helpful.
If your intent is to embarrass, you're not going to win. If your intent is to help little Johnny improve so he will function better in society, you might have a shot. Good luck.