The Straight Dope standard:
That may be a better user name than Cecil.
No problem, they are British, who invented a language they cannot speak.
But I digress.
That is pronounced “Sess sull”. I see no confusion.
It’s actually a valid user name, tied to an active user 
My license plate frame says “OG SMASH” — does that count?
(ETA: I just realized that it’s exactly seven letters if I leave out the space, which is exactly the custom plate limit here in the Soviet. But I don’t know if I want to shell out the extra fee every year.)
I wouldn’t mind an Eric Stratton-esque handshake: a smile, a firm grip and “Hi, I’m @username, damn glad to meet you!”
Well, shucks.
That’s the password!
The countersign is “You bet your sweet ass I am.”
Yes, it’s a look, but the it’s subtle because “the look” varies. For instance, no socks at all (too hard to put on) and dog hair on the clothes (Dopers love pets, but it’s long been established that maintaining a cat-house isn’t the only way to do it!). Also, a perpetual scowl that suggests annoyance with the world, which is not unfolding according to the preference of the subject under study, is more evidence that the subject may be a Doper.
This is it.
What did you do to get so lucky?
Merely say to a suspected Doper either of the following: “I think ketchup on a hotdog is an abomination”, or “I think beans in chili should be punishable by death.” If no hour-long dissertation on the wrongness of your beliefs doesn’t ensue, or the person bolts for the exit, then it’s an ordinary citizen.
Of course, dog hair or a chewed up toe on your sandal. Maybe a bit of duct tape to hold straps on.
Just say, “Look, I could’ve had my sandal fixed professionally, but I did it better and cheaper at home. Do you know what direction the colonostomy surgical suite is, per chance?”
Yep.
Doper will show themselves.
They’re kinda like goalposts, except they move.
We have a neighbor with a pet cat named Opal. They’ve never admitted that they know of SDMB. Must be staying incognito until I come up with the secret handshake.
Wow, I was just thinking about her yesterday.
That’s it. That’s the secret handshake, right there. “Are you a friend of Cecil?” A “Yes” means that you are a Doper. A “What? Huh? I don’t get it,” means that you are not.
I suggest that we adopt this as our secret handshake: “Are you a friend of Cecil?”
I don’t know if there’s a general password, but if you see someone surfing the Dope on their phone, the magic words are, “It’s taking longer than we thought.”
The good news is, there is a secret handshake, and I can tell you what it is.
The bad news is, you don’t have enough tentacles to be able to perform it yourself.
I thought the phrase was “Do you have a minute to heard the Word of Og?”