The egg and the safe

A wife noticed there was a safe hidden in her attic. So she asked her husband “what’s with the safe?” So he told her “I’m not sure but don’t look in there while I’m in the market!” After he went out she became curious and it ate away at her thinking of this safe in the attic. Finally she gave in and looked in the safe and found £40,000 and 3 eggs. Confused by this she waits for her husband and confronts him. The husband admittedly tells his wife “it’s my safe and I get an egg every time I’ve slept with a woman outside our marriage.” The wife thinks that 3 times after 40 years of marriage isn’t all that bad but, asks “where did the £40,000 come from?” The husband proudly says “every time I get a dozen eggs I sell them!”