In reference to Call of Duty games, it is a fancy way of saying "Nobody will hear me" when you are sneaking into or out of a house or other building you weren't supposed to leave/enter to begin with.
Buddy: Dude, are you seriously going to come with me later? Won't your parents hear you?
You: Relax, I'm running Ninja up in this biatch.
You: Relax, I'm running Ninja up in this biatch.
by AL_PS3 February 14, 2011
In reference to the Ninja/Ninja Pro perk of the CoD games. It's basically a fancy way of saying that you don't have trouble being quiet/sneaky.
Most often used when your friend is worried about you making noise when sneaking out of or into your house.
Most often used when your friend is worried about you making noise when sneaking out of or into your house.
Teen 1: C'mon man, let's go!
Teen 2: Did your dad hear you?
Teen 1: Relax buddy, I'm running Ninja right now.
Teen 2: Did your dad hear you?
Teen 1: Relax buddy, I'm running Ninja right now.
by AL_PS3 February 11, 2011