Fighter Command late 50s. Squadron pilots were required to participate in regular aircraft recognition tests. Every so often the tests would be marked at Group HQ and the results sent to the squadrons. FC targets were Eastern Bloc bombers and fighters. Pilots had to know the wing span of their prospective targets in order to set their gun sights for each target. Fighters were generally about 30ft wingspan and bombers 50 ft.
The tests required the actual aircraft to be identified, but Flt Lt Bloggs disagreed, and completed his tests with "Large" or "Small" instead of aircraft types. It was reported that a message was received by the Squadron Aircraft Recognition Officer along the lines of "Please inform Flt Lt Bloggs that if he continues to submit such test reports, he will get my large up his small. Signed AOC"
Or so I was told.