I feel like I want to make a joke about this guy's kid.
Why do you want to make that kind of joke?
Because he's always making jokes about me when I make mistakes. He's rude.
You really shouldn't make fun of someone's kid. That is horribly rude, even if he did the same thing to you.
But it would be really funny.
If you're having a problem with this guy, then you should try to resolve it with him through communication, or simply cut in contact with him. There's no reason to bring his kid into this, and if you insult his kid then you'll only be escalating the conflict.