Pan-Pan -
"Pan-Pan" is used when there's a problem but the situation is not deemed serious enough and no lives are at risk, so using "Mayday" would be overkill.
Code Adam -
This one is used in several public places, including malls, airports, museums, and hospitals. It means that a child has gone missing.
Code Oscar or Mr Mob -
Shouting "Man overboard!" is probably not the best option in a crowded vessel. Instead, "oscar, oscar, oscar" is used.
1488 - Used by white supremacists around the world, if you see this number in an email address, a t-shirt, or a tattoo, you'll know the person has a Neo-nazi ideology.
Code Red - A "Code Red" used in the context of a cruise line, means that there is a serious illness outbreak onboard.
PEBKAC - If you ever spot a tech guy referring to your case under this code, you'll know the problem is you. PEBKAC means Problem Exists Between Keyboard and Chair.
Bravo, Bravo, Bravo - If you're aboard a cruise ship and hear this one, you'll know there's a fire or another serious incident.
U.S. police use a whole lot of 10s -
American police have a number of codes starting with number 10. Examples include 10-35 for a major crime alert, and 10-89 for a bomb threat.
Protein spill -
If you happen to throw up at Disneyland, employees will refer to the incident as a "Protein spill" or a "Code v."
Code Winnie -
This is the code used when kids pee in the swimming pool at Disneyland.