Typically, "code orange" refers to a specific warning announcement over a hospital's public address system. Code orange can denote a bomb threat, a radioactive spill, a disturbance by a potentially mentally ill person or a mass-casualty disaster.
"Code orange" is also used by schools to alert staff and students to the possibility of terrorist activity in the vicinity. This is likely a carry-over from the Department of Homeland Security's defunct color-coded terrorism threat scale, which indicated levels of perceived threat of terrorist attacks.
Code Orange, formerly known as Code Orange Kids, is a hardcore punk rock band from Pittsburgh, Pennsylvania.