Here's how it works:
* Literal meaning: A baby or young animal has recently been born and their ears are still wet from amniotic fluid.
* Metaphorical meaning: Someone who is "wet behind the ears" is like a newborn, lacking the knowledge and skills needed to handle the complexities of the world. They are new to a particular situation, profession, or experience and therefore vulnerable to making mistakes or being easily fooled.
Examples:
* "Don't send that new intern to negotiate the deal. He's still wet behind the ears."
* "She's a bit wet behind the ears, but she's eager to learn."
The metaphor emphasizes the lack of experience and the potential for learning that comes with being young and new to something.