An unlicensed pharmacist or drug dealer who does not like any communication - other than face-to-face communication - that involves terms associated with the commerce of illegal drugs.
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.
You know that new guy I'm getting my drugs from? He's a total CIA person. He really laid into me when I went to pick up this bag, since I'd sent him a text message asking him if I could come over to get that 8-ball and quarter sack.