Those sort of announcements are intended as shoplifting deterrents. Anyone shoplifting, or thinking about doing so, would panic and not steal. Or so it was thought.
Where I volunteer it is:
Code Blue - Cardiac Arrest/Medical Emergency
Code Red - Fire
Code White - Violence/Aggression
Code Purple - Hostage
Code Yellow - Missing Person
Code Black - Bomb Threat/Suspicious Package
Code Grey - Shelter in Place/Air Exclusion
Code Green - Evacuation
Code Brown - Chemical Spill/Hazardous Material
Code Orange - Mass Casualty Incident
Those are copied off a little card all staff and volunteers get. I have actually only ever heard Code Blue and Code Red pages (I understand I just missed a Code Orange one day).
My old hospital did that too, and if twins were born, they would play it twice in a row.
During December, it would be the same melody, with a jazzy Christmas vibe.
We joked that they should play that death march whenever someone died. 
Surprised nobody’s mentioned that (maybe it’s TOO common knowledge), but Walgreen’s uses the code “IC3” over the intercom when three or more people are in line at the register. It’s a signal for another employee to open a second register.
And yeah, it’s a pun. “I see three.” Can’t unhear it.
I spent about six weeks as an all-day-every-day visitor to a cancer ward. I had a similar thought: Roughly speaking, births = deaths. Yes, world population is growing, but most of that is not in the US. And yes, the US population is growing, but most of that is immigration. To within a few percent, US births = US deaths.
So every time they played the lullaby I thought of two people: a new infant popping into the world then being wheeled out with Mom to go home, and somebody else leaving the world then their body being wheeled into the fridge in the basement.
That thought didn’t improve the experience of hanging out there day after day, week after week.
Is there a punk-cover of Brahm’s Lullaby they could play for stillbirths?
------>hellinahandbasket
Some hospitals use “Doctor” codes–that is, paging a particular doctor, where the doctor’s name is actually a code word. Supposedly this is to avoid alarming patients.
One time my mother was visiting someone in the hospital, and heard a page for “Doctor Blue.” Knowing about the use of doctor codes, and also that “Blue” traditionally means “heart attack,” she was puzzled that none of the nurses or other staff seemed to be altering their routines. She was curious enough that she asked about it. One of the nurses told her, “No, that’s not a code. There really is a doctor on staff whose last name is Blue. That page just means he has a phone call.”