As well as 'Bart', Homer often refers to him as 'boy', 'the boy', or 'you little...'.
Either he is too disrespectful or,as my brother said, Homer is his step father(although my brother does trick me a lot). So i cant be too sure of that one.
Well it`s hard to explain my answer would be that homer does that when his angry. Honestly I don`t know why but it`s a part of a bond they share.
He calls it spider pig and harry plopper
True