When I was a kid, I always wondered what "professional courtesy" meant. I thought it had to do with doctors getting special treatment, but the whole concept seemed murky.

I've come to understand that professional courtesy is essentially a favor bank for grown-ups. It works in all sectors and at all levels. Doormen, teachers, cops, lawyers, doctors, and even CEOs extend it to each other on a daily basis.

When I led communications for a company run by a ...