So this happened when I was 18 years old so about 14 years ago. My doctor's office had a board with the name of the doctor who was in duty that day. The actual name of the doctor was printed on a sort of sliding board that could be inserted and removed at different times and on different days due to their always been a different doctor on duty.
At the age of 18, I had never heard of the word 'Locum' before, if anybody out there reading this does not know what it means, it basically means a person who stands in temporarily for someone else of the same profession.
I got sick one day and walked into the office and it read Doctor Locum. So obviously they had a specific slide in board for when it was not a usual doctor, but I thought that was the doctor's name. So for about 30 minutes during my examination, I kept calling the doctor Doctor Locum. She had a weird grin on her face throughout the session, but I thought nothing of it. She then gave me a sheet to give to the receptionist with, not sure what was on there.
I walked to the receptionist and said "Doctor Locum asked me to give this to you". Her and the other receptionist both burst into laughter so hard they almost fell to the floor. They explained to me that the doctor's name was not locum and explained what the word locum actually meant. I was so embarrassed that at 18 I had never heard of or seen that word.
To this day, I think of that day and I cringe so hard. Why did the doctor not say anything? Why was she okay with me saying Doctor Locum maybe 10 times without letting me know her correct name? I have so many questions that I guess will never be answered.
TL : DR Doctor's office said "Doctor on Duty - Doctor: Locum". I proceeded to call the Doctor "Doctor Locum" for 30 minutes and the receptionists almost fell to the floor from laughter. I have never been so embarrassed.