"Shared secret" is the cryptographic term for a password -- it's something you can use for authentication because only you and someone else (the computer, your security alarm system) know it (as opposed to e.g. public key systems like RSA[1]).
Here are some
evwhore shared secrets:
On 101N in Marin, in the left two lanes just before the Lucas Valley Blvd. exit, there are a series of test marking strips on the roadbed that cause your tires to make a beeblebeeblebeeble sound as you drive over them. I have a friend who use to live in Marin that I used to joke with that if we ever got caught up in some sort of government kidnapping conspiracy scenario (we were both big X-Files fans) we could drive over this stretch of 101 and go "beeblebeeblebeeble" (you know the sound you make when you run your index finger up and down your lips) and figure out whether it was really him in the car or some doppelganger stand-in according to the reaction, because it was a silly moment only the two of us had shared[2].
In a similar mental space, I had a boss (long ago) who was, shall we say, rather large (I don't just mean large, I mean LARGE)[3]. His name is Merle. So you can see how, to me and a comparably immature friend in college, it was riotously funny when I once described the gap in an entryway as a "two-Merle gate."
All of this is by the way, as background information to introduce the following term:
Once upon a time[4], I was on my way back from somewhere, and thought "Man, this cab driver is all over the road. Oh wait, *I'm* driving." (Which, I hasten to add, was merely a whimsical thought for comedic purposes -- at no time did I seriously believe that someone else was in control of the vehicle; but it was funny to have that thought run through my head.)
Having related this story to some friends, since then in communications with them, "cab driver" is an adverb, as in "cab-driver drunk." Which I am at the moment, maybe [4, bis].
[1] This may not be strictly accurate, but I'm kinda drunk, which is sorta the point of this entry.
[2] Until now. The friend in question long ago lost touch with everyone else here in the Bay Area and is widely considered a pathetic loser by everyone who's still here -- if you're reading this, what, it would kill you to keep in touch with us once in a while? Jerkoff.
[3] In hindsight I feel bad for making fun of him for his size, especially because he always treated me very fairly, even though at the time I was a snotty, arrogant shit just out of high school.
[4] In case this ever becomes part of any legal proceeding, I must state that all events described in this entry are entirely fictitious and any resemblance to persons living or dead is entirely coincidental.