In the early 1960's my family spent a week at a 'family camp' event hosted by a YMCA camp facility in the foothills of the Smoky Mountains. There were multiple families participating, with circa a dozen pre-teen children. We were housed in rustic cabin bunk-houses on forested slopes surrounding the camp's central area (mess hall, pool, etc.). Forest trails led to each of the cabins. At night the trails were sparsely / spottily lit by electric lamps hung on trees.
As the week went on we got into the habit of all us kids doing something on our own after dinner, while the adults lounged at the mess hall. One evening we kids gathered in my family's cabin and spent a couple of hours telling scary stories (The Hook, ghosts, etc., etc.). It had become dark with forest sounds outside, and some of the younger kids wanted to hike down to the mess hall to see their parents.
We set off down the trail as a group. Suddenly, one of the younger children pulled up and gasped. I looked down the trail to see a large rippling / undulating white blob floating about a meter above the trail and moving toward us. We all shrieked and ran willy-nilly uphill to the cabin in a blind panic. At the cabin's threshold I launched myself into a dive across the plank floor, landed hard, and rolled under one of the corner bunks in one continuous motion - easily the most gymnastic maneuver of my life to that point.
As we all lay cowering and whimpering heavy footsteps came onto the cabin's front porch and trudged to the front screen door. The screen door creaked open ... The youngest kids began blubbering ... My heart seemed to have stopped ... :shock:
... And then I heard the voice of my quite rotund father ask, "What the heck are you kids doing?!?"
He was wearing a t-shirt with dark pants, and his jelly-belly had provided the undulation mechanism. In the half-darkness and faint overhead illumination on the trail it made for a very convincing flying ghost.
Of course, we'd primed ourselves with the scary stories, and little convincing was required ...