I remember once checking in at GLA for an EK flight. I was in the J queue and the agent, as she was about to tag my bag, told me I should have used the Y queue as I wasn't flying business or Skywards Silver. After my concerned expression that I was in J, apologised as she had taken the first five letters of my 9 letter surname and matched it to someone with the same first 5 letters. Blushes all round.