Code blue
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Code blue is a phrase apparently to be used by any Galactica crewmember who identifies a humanoid Cylon aboard.
Chief Tyrol forcefully shouts "Code blue!" once he sees what he knows to be a second copy of Brother Cavil step off one of the Raptors returning from the SAR for the Caprica resistance. As the priest has been giving counsel to Tyrol at the time of the mission, he knows that Cavil has to be a Cylon (TRS: "Lay Down Your Burdens, Part II").
Notes
- According to the podcast for "Lay Down Your Burdens, Part II", the term is what someone would be shouting "if you saw a Cylon and you knew it." Moore explains the term was chosen because "code red" was too reminiscent of Star Trek's "red alert."