Yep, it's very safe. And when they all get the jokes - when you can say two words to a sib in the middle of a conversation with other people, and the sib doubles over laughing while everyone else stares at you - it's really easy to just exclude outsiders. It's like FR. If you went somewhere else and used "series" or "vey", they'd think you were stupid, or a careless typer. I've got a whole vocabulary I use around my family that I don't use anywhere else.
"I've got a whole vocabulary I use around my family that I don't use anywhere else."
Also family quotes are hard to explain to outsiders. Our family has a list of classic "sayings" attributed to each family member which can be quoted randomly at any time.
That Kenshin manga development sounds like good news for you. Just wish there was a Barnes & Noble within 100 miles of here--sigh. . .Oh, well, I still have more SP for now, at least.