Of course, the trouble with keywords is that one can easily substitute meaningless alternatives…
When i worked for BT and we would carry out maintenance work, if we had to bring circuits down we had to check to see if they were in use. if they were we would wait a bit and if they stayed up we would have a quick listen (against the law but it’s the only way to find out why a phone line is in use at 4 in the morning).
Invariably the discussion would be rather odd and would definately use code words but seemed to revolve around chaps called Charlie, Henry and Harry for the most part. They were busy lads them three. Everyone seemed to know them and wanted them to come round.