Complex sentence: "Hit Me Up", a term popularized by users of the social networking website MySpace, refers to contacting a person via electronic means, in this case, with a romantic interest for the person being "hit up".
Split into simpler sentences: Hit Me Up, a term popularized by users of the social networking website MySpace, refers to contacting a person via electronic means. In this case there is a romantic interest for the person being "hit up".