We had one of those in our old neighborhood. He was a couple years younger than my boys and the baby of his family, and apparently spoiled to death as a result. My boys didn't really like playing with him because he'd whine and cry if he didn't get his way. And he'd knock on the door about every 5 minutes. "Are the boys done their homework yet?" I'd tell him "No, you'll know they're done because they'll be outside playing."
Five minutes later. "Are the boys done their homework yet?" Ugh!
One day he had been especially naughty, helping himself to snacks, getting the boys in trouble by spilling and saying it was them who did it. (I caught him in his lie by saying one did it, then the other, and how it happened kept changing.) He had his coat on and was standing in the living room. I told him he needed to go home and he said "I can't find something!" Mind you he wasn't even looking for it, but just standing in the middle of the room. I asked him what it was and he said "None of your business!!"
I told him "M, I do not let my children speak to me that way, nor will I allow you to speak to me that way. You need to go home, and if we find something that does not belong to my boys, we will bring it by to see if it's yours." He finally left. I do not miss that kid.