Across from them, they see a man hobbling and barely able to walk.
The first doctor says “Poor guy, looks like he suffered a devastating back injury. You can tell by his posture and the way he’s shifting his weight.”
The second doctor says “I disagree. I think it’s a hip injury, look at the way he’s favoring his right side.”
So the two doctors go back and forth on their analysis and out of competition they want to see who’s right. They cross the street and approach the man and ask who’s correct in their analysis of his injury.
The man says “Well docs, I appreciate your analysis of my situation. You think it’s my back and you think it’s my hip, and I thought it was only a fart.”