baker’s dozen

Example It was a very large nest, with a clutch of about a baker’s dozen of eggs in it.
(Note In medieval England the baker was an unpopular figure, selling at high prices and trying to cheat customers by giving short weight. Strict penalties were introduced in 13th-century legislation, and in order to avoid these (and to make themselves more popular) bakers started to introduce an extra loaf, called a ‘vantage loaf’, with every 12-loaf order. A ‘devil’s dozen’ is also 13, and was a reference to the number of witches who were said to congregate at a summons from the devil.)