Sqn Ldr walks into ATC tower & spots a young SAC counting up the tea bar takings.
Sqn Ldr, "Morning young lady, do you happen to have change of a ten pound note?"
SACW, "Certainly, I'll just count it out for you."
Sqn Ldr, "Hmm, aren't you forgetting something young lady"
SACW, "Sorry?"
Sqn Ldr, "As you can see, I'm a Sqn Ldr in Her Majesties Royal Air Force and as such, I do believe that I have earned the right to be addressed as 'Sir'. Shall we start this conversation again?"
SACW, "My apologies sir, certainly."
Sqn Ldr, "Excellent, do you happen to have change of a ten pound note?"
SACW, "No sir."