To ensure accuracy Bakers back in the day (the medieval days) would add an additional loaf or slice of bread to an order for a dozen to make sure they weren't short selling on weight. Thus, a bakers dozen was born. For more about this practice, and the origin of the term, click here . Today a bakers dozen refers, most commonly, to 13 of something. Kids, food items, etc.   Now my mouth is watering for all sorts of baked goods. Hmmmm....