What is the meaning of got a big in idiomatic expression?

"Got a big in" is not a recognized idiomatic expression in English. It's possible you're thinking of a different phrase, or perhaps you've misheard something.

To help me understand what you meant, could you please provide:

* The full sentence or phrase where you heard "got a big in"

* The context of the conversation or writing where you encountered this phrase

* Any other details that might help me understand the meaning

For example, did you hear it in a movie, a song, or a conversation?

Once I have more information, I can try to figure out what you're looking for.