When you're so down bad that you need an extension of the phrase to define just exactly how down bad you are. This version of down bad doesn't always have to be applied sexually. It could mean you're down bad for a delightful date, or you're just doing shitty in life overall.
In other words, you're either doomed or desperate as hell.
Chad: "Bro, my girlfriend broke up with me AND I failed finals."
Brad: "Man. You down badarious, dude."
Nickname given to bales of marijuana thrown overboard or out of airplanes. Origin is reportedly from members of the US Coast Guard in the area of Southern Florida.