From Fate is the Hunter by Ernest K. Gann;

"We waited, holding the course to the east. I tried calling Corumba again. Silence. I began watching the clock on the instrument panel; my eyes were drawn to it again and again although I knew very well that less than a minute intervened between each inspection. And suddenly I knew that Park was doing the same thing. I found this more amusing than worrisome. We were playing a game which was as old as the combination of two men flying side by side in the same airplane. The game has no offical name, but it might be called "I-have-nerves-of-steel...as you see." The game is usually played while awaiting clarification or the resolution of a situation which is likely to be distressing.
Park was obviously an expert at this diversion, and I found it extremely difficult to match his nonchalance. He was cheating, though. Three times I caught him moving the facsimile slightly to one side so he could see the clock. Conversation is always held at a minimum during this game and we followed custom exactly.
"Anything on your side?"
"No..."