This is when largest and strongest person of a group gets to point of anger where they will end up hurting and or killing someone. The person saying this (The Tank) will most likely announce that horror and terror will be in the near future by screaming the phrase the dog is out. Usually, there will be some barker to imitate a dog that will occur from the person who has let the dog out (The Tank). One should hope to never have to see this happen.
What? Oh damn the dog is out now.