I'm Spanish, just in case some of you think this question is kind of silly.
I watch TV series in English very frequently to practise my listening skills. The words I've heard in relation to children are:
I wonder whether they are used in everyday speech or not. I looked up the meaning of sport in a dictionary and it says:
(old-fashioned) used when speaking to a boy in a friendly way.
However, the Urban Dictionary says: "the name your dad calls you by that makes you feel like a total loser".
As for champ, I think it's a shortening for champion, but according to Urban Dictionary it can be used in a pejorative way, "sarcastically to disparage someone's ability".
And the last one is kiddo, so that would be "(spoken informal) used by adults to address a young person". I like this one because it seems that it's always used with endearment.
So, what's the actual usage of these words? Do you ever use any of them? What words do you suggest I use for this purpose?