You're the guy that wears a coller right?
At least ten year olds don't play dress up.
But in seriousness you aren't that mature yourself to be honest. Personally in my opinion kid is also a sort of figure of speech. I would describe you as a kid myself. You are really immature from what I've seen. : /
- Hey... I have my reasons
-True I'm not the most mature but at least I don't have to stoop to petty insults and name calling.
Also Kid comes from a long time ago, kid means baby goat and when a child acted up someone would be like "LOOK AT THAT KID!" calling them a goat for how they acted, over time it just caught on and now they share the same name.