Not Red Don't Shoot. A security policy used by alliances in the popular MMO Eve Online. Basically means that unless a person is red (and therfore either has low standings with you or is at war with you) you cannot shoot them.)
Pilot 1: Hey I see some dudes here, I'm gonna shoot them
Pilot 2: Don't, we are under NRDS remember?
Pilot 1: Oh yeah...