When you say them in public and people are just like what the heck are you talking about? And you laugh and feel bad not explaining but you don't want to explain because it's an INSIDE joke! Not and outside joke.
One time, somewhere I heard that if you smile at someone you might make their day just a little better because you never know what that person has been going through. Maybe all they needed was a friendly face and a smile.
I have me bestest friend and my best friend. When my best friend says something, probably random, my bestest friend and I laugh about who knows what-inside joke. My best friend gets frustrated and loved us anyway 😂😄😙