When discussing chilis, the term "alarm" (as in Five Alarm Chili) refers to a single type of pepper, or "heat" source in the recipe. A Five Alarm Chili therefore has five different types of peppers.
The current Pepper Spray on the market can be considered to be only one alarm because the "heat" source
is just super concentrated capsaicin (which is the active ingredient in peppers that makes them "hot"). This has limited the absolutly punishing, debilitating power of the weapon, until the recent invention of Two Alarm Pepper Spray.
Two Alarm Pepper Spray is composed almost exactly like normal pepper spray, with the exception that it contains a highly flammable accelerant, and the nozzle of the spray can is extremely high friction.
The second alarm is real fire. Asshole!
(for less serious offenders: dont hold down nozzle until fire comes out)