SWAT – the Strategic Weapons and Tactical force
The SWAT force is called in when there is a highly volatile situation needing immediate, tactical force to deal with the situation.
However, Internet trolls have taken to using the SWAT teams around the country as their very own revenge squad. If you are active on the internet, especially in the gamer community, you need to prepare yourself for possibly being SWATted (having the SWAT team dispatched to your home to deal with a falsely reported violent encounter).
Digg.com has a very good article explaining this, and what you should know.