What does this mean, my friend called me this, should i be mad?

It means that you're "engrossed" with him. Like you can't stop thinking about him or you keep staring at him...Just tell her that you like him and ask her how would she like it if you made fun of her if she liked somebody. But friends are better then a bf so try to stay friends with her and just try to get her to accept the fact that you like him.