Back when I was in college around 1981, I had taken a red-eye flight from SFO to ATL. It was probably around 5:30 in the morning and I was waiting for my connecting flight in a very empty Atlanta airport. I see coming down the concourse towards me is Muhammad Ali and two big bodyguard types. As he approached, we made eye contact and I gave a small nod and he did the same. He then continued on his way.