baker’s dozen, a phrase that denotes a cluster of 13 items, was first recorded in a pamphlet titled Have with You to Saffron-Walden, published by Thomas Nashe in 1596. According to John Hotten’s Slang Dictionary of 1864, the phrase arose from bakers’ practice of providing an additional free loaf whenever a customer bought 12 loaves, in case the loaves were underweight. The penalties for selling underweight bread were indeed severe (ranging from fines, to the destruction of the baker’s oven, to the pillory), and in England they dated back to a thirteenth-century statute known as the Assize of Bread and Ale. However, Hotten’s commonly cited explanation is probably incorrect.
