From Real Life Villains Wiki

Swatting is the harassment tactic of deceiving an emergency service (via such means as hoaxing an emergency services dispatcher) into sending a police and emergency service response team to another person's address. This is triggered by false reporting of a serious law enforcement emergency, such as a bomb threat, murder, hostage situation, or other alleged incident.

The term derives from the law enforcement unit "SWAT" (Special Weapons and Tactics), a specialized type of police unit in the United States and many other countries carrying military-style equipment such as door breaching weapons, submachine guns, and automatic rifles. A threat may result in the evacuations of schools and businesses. Swatting is described as terrorism due to its use to intimidate and create the risk of injury or death.

Making false reports to emergency services is a criminal offense in many countries, punishable by fines and imprisonment. It causes money and tax dollars to be wasted by the city or county when responding to a false report of a serious law enforcement emergency. In California, swatters bear the "full cost" of the response which can be up to $10,000.