The series of bodily changes that occur in the female of most mammals from one period of estrus to another. The estrous cycle usually takes place during a specific period known as the breeding season, which ensures that the young are born at a time when the chance of survival is greatest.
ear-to-ear. It's about smiling. Ear-to-ear smile or grin is when you have a very broad and generous smile. Such a smile when each corner of your mouth is by each of your ears. Explain to me why you don't have an ear-to-ear grin right now.
Vote for this answer. To have someone 'box your ears' is to be hit across the side of the head with either a flat or cupped hand. A very dangerous action, it can burst the eardrum. Where it comes from though I haven't been able to find out.