over 30 years ago I used to go and see an 80 year old man down the road who was a very enthusiastic radio ham and he used to always be saying CQ CQ CQ DX. He told me that it meant "seek you distant station". All the other codes he used started with a Q and meant Question or reQuest. I don't know if thats true but this ICAO list seems to back him up.
Ralf D. Kloth DL4TA - List of Q-codes
he was a nice old chap. One of the founders of the radio network that went along the trans canada railway. He let me shoot a breeze block in the shed with a luger that he got in the war on fireworks night once. My ears are still ringing.