OD'd is taking too much of a certain drug or medicine. It's short for overdosed: something that can lead to either extreme happiness, or long periods of misery. Often times the latter.
Samuel: Yeah, Michael OD'd on his meds last night.
Jonathan: Haha, he's probably trippin' balls right now, huh?
Samuel: Sorta. He's crawling around in a fetal position.
For when a batchelor/stag gets married before having his final night with his boys and is permitted one night in lieu to have his stag do...because it is after the event it has to be spoken backwards.
J: Hey M, when the hell are we gonna have your stag do.
M: I can't anymore as I'm married.
J: Well there's only one thing for it. OD GATS!!
A: I love a good Od Gats.
OD means over doing. An OD master is always one who is always over doing it, and to his or her best abilities. Likes to be on top of everyone and over does everything to it's maximum.
A secret society group at Oxford University made popular through their high levels of steez in all aspects of life. If you are an OD you represent excellence in all facets of university culture - sport, academics, clubbing and gyming.