Doctor. Doctor. Doctor.

When several people of similar (and high) rank or professional stature are gathered, and greet each other with their titles. For the principals, it is short hand for "Wow, we are all really awesome and successful. Isn't that awesome?" For the audience, it serves to point out that this is a meeting of Big Wigs, who will make Important Decisions and discuss Important Things.

The script would look like this: "Chase: Doctor. [shakes hands] House: Doctor. [shakes hands] Foreman: Doctor. [shakes hands] Cuddy: Doctor. [shakes hands] Cameron: Doctor. [shakes hands]"

Seen with doctors, high ranking military officers, and members of nobility and aristocracy. A variant is to have introductions between people with the same name. This trope is almost always played for laughs, and happens to be Truth in Television.

Not to be confused with the 1989 sitcom Doctor Doctor

Film
"Prot: "Doctor — Doctor — Doctor — Doctor. How many doctors are there on this planet?""
 * K-PAX, at the planetarium when Prot and Dr. Powell meet four astrophysicists. See clip

"Tower guy: "We're all ready sir. This is Captain McCrosky, Captain Roberts, Captain Kramer, Captain Kolosomo. Captain Henshaw, this is Captain Gatz. Captain Kramer, Captain Gatz. Captain Henshaw, Captain Roberts...""
 * Catch Me If You Can, when Frank pretends to be a doctor.
 * Kermit and Pepe do this in Muppets from Space.
 * Spoofed in Airplane!

"Travis: My rank is colonel. Crockett: So's mine. Wouldn't we sound silly jabbering "Colonel, Colonel" at each other like a couple of bluejays?"
 * Spies Like Us has this as an Overly Long Gag, punctuated by a guest shot by Bob Hope. Watch it here.
 * Defied in the 1960 film The Alamo:


 * "McQueen, the Queen. The Queen, McQueen."

Literature

 * Honor Harrington is filled with scenes like this, and as Honor rises in society, the volume of Dukes and Admirals only increases.
 * Early in Isaac Asimov's Black Widowers series of short stories, it was stated that the members of the club grant themselves and their guests an "honorary doctorate" within club meetings. This eccentricity came up once or twice in later stories, but served no real purpose. It was mentioned at the start that someone who holds an actual doctorate, such as Widower James Drake, is thus, for instance, "Doctor Doctor Drake." Emmanuel Rubin claims to have enough other honorary doctorates to be "Doctor Doctor Doctor" all by himself ... and he was interrupted after the third "doctor," so there might be more.
 * One of John Dickson Carr's murder mysteries features Intrepid Reporter James Blake visiting New Orleans to interview rising politician James Blake. Fortunately, the latter Blake normally uses "Clay" (from his middle name) among friends, and the two quickly get along quite well, but there's a moment when the politician's secretary phones the newsman and says, "Mr. Blake's anxious to see you, Mr.--he's very anxious to see you, I know."

Live Action TV
"Doctor: Mr. Bertenshaw? Mr. Bertshaw: Me, Doctor. Doctor: No, me doctor, you Mr. Bertenshaw. Mr. Bertshaw: My wife, doctor... Doctor: No, your wife patient. (etc. etc. etc.)"
 * Stargate Atlantis: as seen in this clip.
 * Supernatural: When Sam & Dean are Trapped in TV Land as doctors on the set of "Dr. Sexy M.D." and they meet the eponymous Dr. Sexy.
 * The Big Bang Theory: clip.
 * Spoofed in a Monty Python's Flying Circus sketch (in Episode 13):

"Fourth Bruce: Goodday, Bruce, Hello Bruce, how are you, Bruce? Gentlemen, I'd like to introduce a chap from pommie land... who'll be joining us this year here in the Philosophy Department of the University of Woolamaloo. All: Goodday. Fourth Bruce: Michael Baldwin - this is Bruce. Michael Baldwin - this is Bruce. Michael Baldwin - this is Bruce. First Bruce: Is your name not Bruce, then? Michael: No, it's Michael. Second Bruce: That's going to cause a little confusion. Third Bruce: Mind if we call you 'Bruce' to keep it clear?"
 * Monty Python's Flying Circus: "Bruces" sketch, when Michael Baldwin gets introduced to the other characters, all named Bruce.

Theater

 * In Anyone Can Whistle, Hapgood explains that this trope is the reason that everyone thinks he's the local asylum's new doctor when he is actually its latest patient.