No you were trying to be insulting, and you know that, same as if people opposing Hillary had called her "girl".
"I have, on many occasions, seen Obama fans refer to themselves as kids."
I haven't. But either way, as people have tried to explain you it doesn't matter. You don't get to decide that a potentially offensive name isn't offensive just because you've seen people refer to themselves as such.
I have seen many times see grown women refer to each other as girls, but that doesn't give any man the right to call "girl" a woman in order to disparage her.
You fail Feminism 101 if you don't know that. You fail Common Sense 101 if you don't see the parallel with that scenario.
Just say you didn't mean to be offensive and avoid doing it again, rather than argue that it's okay because you've seen a few-self references. That argument fails -- it's the very same argument used to justify the n-word from white racists "blacks themselves use it, why can't I", the d-word word from homophobes "lesbians themselves use it, why can't I", and the girl-word from sexists "women refer to themselves as such, why can't I".
