Why do guys pick on girls and won't admit the truth as to why they do that?

This guy is in the same trade as I am and isn't even from the same country as me; that's not what even bothers me. I'm not upset at the fact that he picked on me; what bothers me is why didn't he just say the truth instead of saying shut up-GD. He could of said he was having a bad day and that he wasn't in the mood for it; I would have understood and not say anything then, but he didn't.

Ok, and it got me to think aboyut two alternatives-1. Is he just picking on me to get a reaction out of me? 2. Is he picking on me cause he doesn't care? or 3. Is he picking on me the way guys pick on girls in elemmentary school where guys pull girls hair and girls say, "Ew, yo got coodies stay away from me."-what I mean is is he picking on me cause he likes likes me, but is to embrassed to admit it?

That's all I need to know cause I have a feeling he won't tell me the truth.