A cultural reference to drawing dicks on table tops and other related surfaces. While it is immature and wrong, it can be, at times, hysterical. D's Up is usually a formal way of greeting someone who does this sort of thing.
Guy 1: "Hey man, what's up?"
Guy 2: "Hey yo, D's Up."
Guy 1: "Ah yes, D's Up indeed."
A hardo is a person who tries extremely hard at everything. Most times a hardo will try very hard at things that do not require excessive effort. For example, sports practices, gym class, etc.
Wow did you see Jack at practice today? What a hardo!