The embarrassing thread and the various mentions of Kemper Lakes reminds me of the most unusal thing I have seen/done on a course.
While playing hole 4 of Kemper, one of my group, a good golfer, was grinding over a third shot to the green. I looked up, and saw a single engine aircraft with its motor off drifting down towards him, apparently seeking an emergency landing on the fairway.
I don't know why, but I figured I would warn him after he hit his shot, and as he stood over the shot longer than I expected, I faced a dilemma.
About simulataneously, he finally hit his shot, the plane restarted its engine, no more than 30 feet above his head, and I yelled for him to duck. The plane simply flew off, and I never heard any more about it. We continued our round with little discussion of my attempt to preserve his concentration, under the circumstances.