My friend's ten year old kid said to me "you're a drunk". He was right because I was a heavy boozer at the time but I thought it was a bit of nasty thing for him to say.
I can't recall anything that a person of that age group has called me anything insulting. I was called pathetic by my 57 year old wife 10 years ago, though.
My daughter was never into the insult thing, but my 5th grade teacher told me that if I were his daughter, he'd spank me (because I wasn't very good at math and kept failing tests).
It was a hot day. I was on duty in the school playground, sitting on the bench just watching them all during recess. She sat down beside me, in silence for a little while, and then came out with it.
Since then I've always worn a deodorant when out in public.