When a man is balltagged, but the pain isn't immediate, giving them a delay in which they can enact their revenge before going into pain shock.
Kyle punched my nuts, but I was a dead man walking.
What inmates in jail shout out to other inmates to alert them that a corrections officer (c.o) is walking around close by checking for contraband or illicit activities.
Joker hid the stash when he heard someone yell out "man walking".