My pet hate is the use of either IATA or ICAO airport codes in the "Passengers/SLF" forum for airports which are bound to be unfamiliar to most of us. Are you telling me that it's much quicker to press "caps lock" type in three or four letters, then press "caps lock" again than to write the airport's name?
Frankly, the use of these codes sometimes strikes me as pretentious and even though I use them from time to time, I try not to. Even pilots don't always know to which airports some of these codes apply!