IF I personally know heat they are younger it is a common english phrase or Scottish to rename someone kid if you don't actually know their name, not a problem to me.

I could see how this would get annoying for a 14 year old that thinks "oh im not a kid im a grown man!!" They most likely call you a kid.. Well because your a kid.. does not matter if he is older or younger then you does not change the fact that you ARE a kid.