When making reference to the Middle seat in the rear of a car, the bit with the hump that you have to perch on.
Rules for calling shotgun #8 Once shotgun has been called for the front seat then back left and back right can be called. This effectively leaves the slowest person to travel in the bitch seat.
In your ear stretching/gauging process, it is that ONE EAR. it's the one that is more difficult to stretch, takes longer to heal, and just doesn't look as good as the other ear, and you experience much more discomfort with it. it's a total bitch because it just won't cooperate with you. therefore, it is known as The Bitch Ear.
guy#1 "dude ! my left ear hurt more than the right ear when i stretched it last night."