A reward given to players in Newer Call Of Duty games after killing a certain amount of enemies without dying. Normally consisting of a support helicopter, dogs, or air-strike. Until Modern Warfare 2 was released and gave players many more rewards for camping and being little pansies abusing care packages and sentry guns. Higher streaks include Harriers that hover with chain guns, predator missiles you control and AC-130 and chain gunships that spawn kill.
Upon camping your ass off to a 25 killstreak you can call in a nuclear warhead to end the game, because by that time the entire server is sick of your shit and at least Infinity Ward is self aware of what they did to a "realistic" war shooter.
Smokeytoke420 with a title and emblem of a weed leaf obtained his AC-130 Killstreak where he proceeded to spawn kill the enemy team as they were punished for not camping.