The definition of in-joke implies that it should stay 'in' and not be broadcast as a form of bragging.

I know, right? It just doesn't make any sense to me. Glad I'm not the only one who sees it that way.

I am so cute! I bring a little bag of bread every single day. My co-workers just shake their heads at me. But it's glorious! If you throw the bread just right, the gulls will swoop down and catch it in their mouths, midflight.