Inside Yolk

When you've worked a branding project so long you're delirious, then a yellow circle (intended to be a moon) lands on top of a the 'O' > That looks like an egg! > What's an eggy word that has an 'O' in it!? > Yolk! > What's a pun or idium that I could use yolk in!? > Inside Joke!

That was my random thought process. :P