Baker’s dozen means 13, instead of 12. The tale behind its origin is that a medieval law specified the weight of bread loaves, and any baker who supplied less to a customer was in for dire punishment. So bakers would include a thirteenth loaf with each dozen just to be safe. It is said that during good harvests, bakers sold one excess loaf to middlemen. A baker’s dozen takes on importance in large families, where that little extra goes a long way.