What Does “I wasn’t born yesterday” mean?
Definition:
If you say you ‘I wasn’t born yesterday’ you mean that you are not stupid enough to believe anything said to you.
The phrase refers to the fact that wisdom comes as a result of the experiences one has throughout one’s life. If you compare someone to a newborn baby, you mean that they are naive with no experiences with the world.
Example(s)
You say you would pay me back as soon as possible, but I don’t believe you. I wasn’t born yesterday, you know.
I am not easy to fool. I wasn’t born yesterday.
I know he will not change overnight. I am not born yesterday.
This idiom is in the age category.