When you get hit really hard at the base of your arm and the whole thing goes numb.
Also an amusing game which basically involves a sucker punch in an attempt to kill the other person's arm. Success is met with much hilarity among tards, and wild exclamations of "dead arm".
liek omg dood, my arm is teh dead!
1. . 2. . 3. . *THWACK* HAHAHAHAHA DEAD ARM DEAD ARM AHHAHAHAHA
Basicly, "going postal" is pulling a uzi, assault rifle or most any other firearm out from under your jacket and going nuts. That is, wasting anyone and anything you see, and then probably yourself. A bit like going apeshit.
Jim had left another burning paper bag of crap on John's doorstep, so John retaliated by going postal on his ass.
What happens when two people are walking towards each other on a pavement, but both try to go the same way to dodge each other. That is, one sidesteps to their own right and one sidesteps to their own left. Sometimes the move is repeated immediately after, with the dancers sidestepping in the opposite direction.
John pavement danced with 3 strangers on his way to work.