This includes reference or mention of illegal drugs, terms, amounts, intentions, or other language that would likely arouse the suspicion of law enforcement officers, should they become aware of the communication.
CIA refers to the United States Central Intelligence Agency. It does not mean that the CIA person is afraid that the CIA is monitoring him. Rather, CIA is used to indicate law enforcement agencies and agents in general.
A CIA person will get upset if such language is used in text messages, phone calls, voice messages, or any other communication method aside from the direct, face-to-face type.
A CIA person must assume on some level that his communication methods are being monitored or will be checked by law enforcement, and used as evidence to prosecute him or her in court.