I think I share a lot of inside jokes with people. The funniest will have to be "the birth of the muscle schasm" that I share with my sisters and, now, a friend.
Two years ago, we had to take my sister to the ER because she wasn't feeling well and she was feeling some pain on her back. We were at the hospital for a while and she had to take some tests and we were told later on that it was nothing, just some muscle spasms. as we were getting ready to leave my other sister called, worried, and my little sister answered it.
Little sister: She's okay now. We're about to leave. There's nothing to worry about, it was just muscle schasms!
We couldn't stop laughing and we now call spasms, schasms! In fact, when my friend fell from the dancing pole, and she had to have some xray done only to be told that she only had some muscle spasms --- I still couldn't stop laughing about it. I had to tell my sister about it and it's really funny how I shared it to her too:
Crix: My friend goes to pole dancing class and she fell. She hit her back really hard and I had to go with her to the hospital. She had to take some tests but she turned out okay. The doctor said there was nothing to worry about and guess what was it that she had?
Little sister: A muscle schasm???
It is still funny as hell!!