The college where I work has a really great cafeteria. Usually I eat w/ my immediate coworkers, but lately I've been mixing it up a little.  One guy I've sort of gotten to know  over the years doesn't work there at all; he just eats there and goes to a ton of campus events and helps with fundraising.  I always figured he was just rich or retired or both.  He always has tons of other intetesting things to talk about, so I never asked.

Today at lunch, just making conversation, I mentioned to a music prof something about my weird elbow pain.  He points across the table at my rich/retired/mystery friend and says "Why don't you ask him, he's the doctor.  After diagnosing my ailment as tennis elbow and giving me tons of advice, I ask him what his specialty was.   Answer : Sports Medicine.