Probably from British Airways, have you ever noticed during the Captains blurb to the pax he is nearly always accompanied by Senior First Officer blogs, WTF is a senior F/O.
Many years ago, whilst on a fam flight [not BA] with a F/O friend of mine, the captain's PA included the "senior first officer" bit. I asked my friend what was the difference between a first officer and a senior first officer.
His reply? "Passenger reassurance!"
Still not sure if he was kidding me or not...