* It's a made-up term: Someone might have created it to describe a specific type of pun they enjoy, but it hasn't gained wider usage.
* There's a misunderstanding: Perhaps there's a related term you're thinking of, or the term has a specific meaning within a certain context.
To help me understand, could you provide more context?
For example:
* Where did you encounter this term? Was it in a conversation, a book, online?
* What was the context? What were people discussing when "POP punning" was mentioned?
* Can you provide an example of what you think "POP punning" might be?
With more information, I might be able to help you understand this term better!