I grew up in a really large extended family, and many of my cousins who were quite a bit older, and all of them talked a bunch of shiz. They would always give my brother and I a lot of crap, and we got really good at dishing it back too, so I know what you mean Linc and Bondo. My mom and my aunts and uncles could lay it down good too.
OTOH, I think what they did to the kid went over the top and just got mean. Its a bit of a fine line, but you don't want to beat down a kid and make him feel bad for just who he is. Esp when its your moms laughing at you. There's a point when it goes from sharp edged humor to tearing someone down to feel like the piece of crap you are. That seemed the later. Hey, maybe if they didn't tear each quite so harshly, they wouldn't be such losers they can't even afford an xbox.
Hard to explain, and its a kinda subjective, but like I said, it would have been funny to me if he did get the xbox or something in the end.
This prank is funnier IMO: