Idiom
A Nest Egg: Origin and Meaning
Meaning
Savings; an amount of money that has been saved for the future.
Origin
Since the 14th century, farmers have been putting ‘nest eggs’ (fake eggs) into hens’ nests to encourage them to lay more eggs. This system works well and farmers often end up with more eggs, meaning more money for them. Due to this, the term ‘nest egg’ meaning ‘savings’ began being used in the 1680s.

Context
“I think we should start putting small amounts of money aside every month to build a nest egg for the future.”
“Son, we worked hard for many years to build up a nest egg and we’ve decided to spend it on your university education.”
Tom: “Are you coming with us to the casino tomorrow?”
Sam: “I can’t, sorry. I don’t have any money to spend at the moment.”
Tom: “I thought you had a nest egg saved up. Why don’t you use some of that?”
Sam: “Oh no, I can’t use that! My wife would never talk to me again! It’s supposed to be for emergencies only.”
“Son, we worked hard for many years to build up a nest egg and we’ve decided to spend it on your university education.”
Tom: “Are you coming with us to the casino tomorrow?”
Sam: “I can’t, sorry. I don’t have any money to spend at the moment.”
Tom: “I thought you had a nest egg saved up. Why don’t you use some of that?”
Sam: “Oh no, I can’t use that! My wife would never talk to me again! It’s supposed to be for emergencies only.”