Nothing makes my teeth gnash more than slicing a loaf of bread and discovering that some accursed bubble has hollowed an end of the loaf: not only do I get jam all over my lap as it drips through the resulting sandwich-cavity, I feel cheated for having purchased bread and gotten air. Such unholy bubbles prompted the English Parliament to pass a statute in 1266 promising severe penalties for bakers whose loaves weighed less than they should. Bakers responded to this new law not by making their loaves bigger—which would have meant buying new sets of bread tins—but by adding a thirteenth loaf to every dozen that the customer bought. These thirteen loaves became known as a baker’s dozen, a term first recorded in the sixteenth century.