On the one hand, way to go, JaVale McGee. It's always important to compete to the best of your ability, even if the competition in question is a game of Pop-A-Shot with a small boy. On the other, I think you are misunderstanding how far away the edge of a Pop-A-Shot machine is from the hoop within. Like, that is nowhere near 3-point distance; successfully scoring 63 points in a round of Pop-A-Shot does not mean that you are a good 3-point shooter. Come to think of it, it doesn't even mean you're a good free-throw shooter — or, at least, it's not compelling enough evidence to overwhelm your 58.3 percent career mark from the stripe. Maybe it means you've been working on your teardrop floater, but I'll need to see it busted out in-season a bit before I believe it, I think.
Also, the answer to "Who says I can't shoot 3s?" is probably, "Every coach you have ever had, including, most recently, George Karl," right? And you don't seem to think that is such bad advice, considering you have only taken five 3-pointers in 367 NBA games, making just one. (But oh, what a make it was.)
On the plus side, at least you didn't have to cheat to win at Pop-A-Shot, unlike this one other 7-footer I know. And now that you've successfully dominated a child, maybe you can step up in competition — I'm not saying we go after the Perfect Pop-A-Shot Game Lady or vaunted busboy Ricardo Reyes just yet, but challenging yourself is an important part of growing as a player and a person. Plus, I bet that if we filmed you going around and taking on progressively older and more skilled opponents, it'd make for a good segment on the reality show, provided your mom's cool with it.