1) An elite group of trained assasins that take on various missions.
2) An action or set of actions that are performed in a tatctical yet badass fashion which result in a) severe bodily harm, or b) large amount of collateral damage.
Bad Guy 1: Holy shit, is that Unit 13?

Bad Guy 2: Hell yes! We better get the fuck out of here.

Bystander 1: Wow did you see that merc Unit 13 all those tangos?
by warmachine1981 February 23, 2010
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