This phrase is typically used as a codeword for "indisposed" by guys from the Northern Virginia (NOVA) area when they are stuck in close-quarters scenarios with girls in Maryland (usually tourists) and need to convey to their bros that they can't rid of or away from the females as easily as they thought, so other plans may be cancelled.
Scene: A guy from NOVA meets up with a couple of girls visiting the DC area who happen to be staying in Maryland. The planned meet runs long and the guy ends up escorting the girls around for hours due to multiple flight delays. While they are in the NOVA guy's truck, driving aimlessly, the phone rings.
NOVA Guy 1: Hello.
NOVA Guy 2: Yo man, what's going on? You still up for this party or what?
NOVA Guy 1: Nah bro, I'm still up in Maryland.
NOVA Guy 2: Ah, shit. My bad...
Later in the day:
NOVA Guy 2: So what happened with those girls up in Maryland?
NOVA Guy 1: Man, I couldn't get those bitches outta my truck.