DAFECON 2 is a serious situation. Danger is imminent. An unusual threat has imposed itself upon Dave's home. The next step is an all-out war.
Here is an example of a DAFECON 2 situation.
Here is another. This one portrays one of the drawbacks of raising the alert level to DAFECON 2 or even higher. Sometimes there is collateral damage. It's just what happens when you are on your toes prepared for a nuclear conflict. Unfortunately, Jack was the innocent bystander who was targeted in this situation.