It wouldn’t really help if one of the students is the bad guy. But if the bad guy isn’t a student, he probably doesn’t know the code. This way he doesn’t necessarily get tipped off that everyone knows.
I worked at a music store around 1989 - 1990 and we had two codes.
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“I need a 26” (or some other number, I can’t remember) means I need someone to come take some excess cash out of my cash drawer and put it in the safe.
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For suspected shoplifting, we would say, “Did we get the [Artist Name][CD/CASSETTE] in from the [FAKE STORE LOCATION] store?”
The suspected shoplifting would be taking place in the area of the named artist’s cassettes or CDs. For example, if some suspect was in the beginning part of the Rock/Pop CD section, we would say, “Did we get any Duran Duran CDs in from the Burbank store?”
Everyone knew there was no Burbank store in real life and, even if there was, we would never expect any kind of product shipment from that location.
If the suspect was in the Country cassette area, we might say, “Did we get any Kenny Rogers cassettes from the Norwalk store?” Etc.
All eyes would then go to that part of the store.
Working in a hospital and we’ve got a whole litany of them. Dr Greenfield (disturbance), Plan D (disaster), Code 2 2 (infant abduction) are a few examples.
The only one I’m really worried about is a Broken Arrow.
I used to work at a Juvenile Prison - The main ‘code’ that we used used was the word “now”. If you needed assistance for some minor matter, you’d say “Assistance needed in [locationX].” If it was an emergency you’d say “Assistance needed in [locationX] now.” Any available staff would drop what ever they were doing and RUN to that location. I only had to call it once. I could here the feet running to my location immediately.
We used our equivalent once in elementary school- a parent who’d lost custody of a child in a divorce and had made some kind of threat to kidnap the child showed up at school. The announcement went off “It’s George Keno’s Birthday!” and all the teachers went quietly into lockdown mode.
My mother, incidentally, had only been working as a teacher at this school for about four weeks when this happened and thought it was a planned event of some kind (George Keno was the town’s founder). She was excited, ready to break out cupcakes and have a party until the teacher next door filled her in.
A friend of mine from law school used to be a lifeguard at a large water park. According to her, one of theirs was “Code Baby Ruth.” It meant there was a turd in one of the pools.
WILDFIRE was the codename for the team. “We have a ‘fire’” basically telling whoever that the WILDFIRE team was assembling and to get your ass in gear.
Subtle. Paging “Doctor Shitstorm”…
I remember Henry Rollins’s character describing Dr Allcome in Johnny Mnemonic.
The term Broken Arrowis also used to indicate a friendly unit is about to be overrun and all available aircraft should immediately bring the noize.
I recall that there’s some obscure organization (heh) that uses the phrase “Is there no hope for the widow’s son?” (together with a distinctive gesture) as a discreet distress signal.
C-3PO makes this particular gesture, perfectly simultaneous with the Leia’s order “Give the evacuation code signal!” during the Battle of Hoth, in The Empire Strikes Back.
You’d be surprised how many movies get just a bit more interesting when you have an interest in Hermeticism. 
Similarly, when my brother worked as a cook at Denny’s, he told me that their restaurant’s procedure was to ask for “Amy” or another common name to report to the hostess’s station. If an Amy was ever hired, the call was for “Lisa” or another name that none of the current staffers possessed. The code was most typically used when a “dine and dash” was suspected to be in the process of being attempted, but occasionally trumpeted something more serious (customer making threatening statements to a waitress, effort to grab money from the register).
While I worked in a hospital, we had color codes (with one ‘doctor’ thrown in). Pink = child abduction. Red = Fire. Blue = Emergency medical needed in room. Black = Tornado weather or other similar natural disaster. Yellow = Massive incoming casualties. Doctor Strong = Combative patient.
I remember we had a code for a patient wandering off, but I can’t recall what it was. I do know that we had to know what to do for every and all codes, and because of that we had them printed on a card we carried attached to our ID cards.
In aviation, in addition to the aforementioned “mayday, mayday”, there is also “pan pan, pan pan”. It’s been a while – I THINK its definition is “I’m in an urgent situation, but not yet an emergency”.
Regarding banks, I remember seeing in some show that local banks had agreed-upon signals with the local police. Setting something in a particular way meant “everything is fine”. Conversely, if the bank had been open for a few minutes already and this sign wasn’t set, the police would assume something bad was going down and bring in the cavalry. Now that I think of it some more, I think this was in the movie Bandits with Billy Bob Thornton. The signal was turning the blinds a particular way. Does anyone know if this is purely a movie construct, or if its real?
J.
At a branch library I worked at 15 years ago, we had two codes. One was a way of offering to take over for a staff person who seemed to be having trouble with a difficult patron: “Teresa asked to see you in her office.” If the staff person felt like they had it under control, they could say, “Okay, I’ll go as soon as I’m done” or something like that, otherwise, they could say, “Okay, do you mind finishing up with Mr. Smith?”
The other was a covert way of alerting other staff that the situation you were dealing with was getting out of hand: “Would ask Teresa to check the thermostat?” That would send them running for a manager to come intervene.
Yes that’s correct. “Pan pan” is used when you require priority but there is no immediate threat to life. If I didn’t have enough fuel to land with my legal reserves I’d put out a pan pan, if I didn’t have enough fuel to make the runway at all, I’d put out a mayday. Not all countries recognise the pan pan call though, so if in doubt, declare a mayday.
Another nautical one is the use of a “V sheet”. An orange sheet with a black “V” displayed is a distress signal. I’ve been called out to a search and rescue for an emergency beacon and when we tracked the beacon we found a small recreational boat displaying a V-sheet–they’d run out of fuel.
When I worked at a clothing store, saying there was gum on the floor meant to watch out for shoplifters.
We participated in the Code Adam program. We were neither Target nor WalMart.
But even if the bad guy is a student, the code probably functions as a euphemism- everyone knows what it is, but are able to be calmer about it. Also, a code can contain complex instructions in a small, hard-to-garble phrase. After all, a fire alarm really means “Walk calmly but quickly out of the building, stand at least fifty feet away from the building, and do not re-enter until you are told. Now!”
Signal for American personnel to move into position for final evacuation from Vietnam in 1975, broadcast over Armed Forces Radio: “The temperature in Saigon is 105 degrees and rising”, followed by Bing Crosby singing “White Christmas”.
In the recent Albertville school shooting in Germany they used the phrase “Frau Koma kommt” (lit. “Mrs Koma’s coming”).
“Koma” is Amok backwards… “Amoklaufen” means " to run amok" in German, and is what they refer to as spree shootings.
It’s the same signal to barricade the doors and get under the tables.
Not exactly the best source (that film was a joke, BTW), but there are other indicators of “less than desirable” events.
I’m not calling Wikipedia worthless, but I have to take this one with a grain of salt. It may have been used in the past this way, but lately I’ve known those radio calls to be locally generated at the AOCs, as in:
"Zotti Five Two this is Cecil actual. Heavy contact, danger close danger close danger close–request help from “THOR”'. (“THOR” being the call for help that day.) It’s been several years since I talked with my bomber-driver pals, but I remember it along these lines.
Tripler
I’ll see if I can’t find one or two to confirm some more details.
Thor would probably do the trick.
Bit of a spoiler about the game Braid (not a huge one though) but knowledge of danger codes sheds light on something that happens at the end of each level.
[spoiler]
There’s a flag next to the castle you arrive at, and it turns out the flags are in a maritime code. They mean, in order, (one flag per level), paraphrased:
No.
You’re heading for danger.
Stop now.
Stop what you’re doing, listen to me.
I need to talk to you.
[/spoiler]In the context of the plot of the game, this is quite eerie.