On amateur (ham) radio, we often use Q-codes, which are three-letter codes starting with the letter Q with various meanings. They were originally used to speed up Morse code communications; it might be necessary to send "Can you hear me between your signals and if so can I break in on your transmission?" fairly frequently, but you would not want to send that entire sentence regularly. "QSK?" is much shorter. Many of the codes still in common use aren't used exactly "correctly"; they've become more jargon than codes. "QRP," for example, actually means "Shall I decrease transmitter power?" and "Decrease transmitter power," but it's more commonly used as an adjective meaning low-power; you might have a QRP transmitter, meaning that the transmitter has a low maximum power setting. "QSO" means "Can you communicate with...?" or "I can communicate with...," but now often means a radio contact (as a noun); a "QRP QSO" is a contact in which one or both operators was transmitting at low power. (I don't use CW and I rarely use conversational digital modes; these codes might be used "correctly" more often on those modes.)
There are (were?) a lot of these codes specifically intended for aviation. Are any of them still used, either the "right" way or as jargon?