"I'm cool." The ears are lowered and point slightly backward. (On a droopy-eared dog, they simply flop.) The eyes are open and calm; the mouth is closed.
"Yo, what's happening?" The ears prick to attention. The eyes are open and sparkling, the mouth is relaxed and possibly panting, the tail straight out and wagging.
"I don't like this!" The ears spring forward into the alert position, then rotate to the side and close to the head for protection.
"One step closer and I'll bite!" The eyes are narrowed, the teeth are bared, the ears are flattened for action, and the tail is held high.