When I was in residency, a co-resident came up to me one day and said, "Hey, I saw your patient with the C9 fracture. I guess he was a giraffe."
"Huh?" I said. (The human cervical vertebrae only go up to C7.)
He filled me in that in a consult note I'd dictated on an inpatient several months earlier, a C9 fracture had been noted among the patient's many injuries. I did a little research and realize I had said "sphenoid fracture."
Except the funny part (or not so funny part) is for the next several weeks of the patient's hospitalization, multiple physicians noted that the patient had a C9 fracture. Some were clearly copied and pasted from my note, but others actually broke down the injuries one by one, still noting the C9 fracture.
The moral is either that people in medicine sometimes don't think, or else maybe it's that I should check my damn dictations better.