[CYO Butch]

Thanks for the derivation. That was a new on on me.
My favorite number reference is not 10-4 (from 2-way radio usage) but actually from an old list of catch phrases and punch lines that made its way around during the 70's. The idea was that if you just used the number, people would know the joke and laugh without having to spend time telling it all over again. The one that I still use to this day is "585". It stands for "Pardon me sir, but I believe you mistook me for someone who gives a sh*t." Fortuantely, the people I tend to say it to are either my close friends to whom I have taught it, or people who don't know what I'm talking about at all.