"Shaggy Dog Stories" relevant to "Cartoon Physics"

[Bystander]

e.g., the pet store/livestock delivery truck driver who avoids being ticketed for driving an overweight vehicle by hitting the side of his closed van periodically to keep the canaries/parakeets/chickens/turkeys airborne.

https://www.physicsforums.com/threads/sailboats-providing-their-own-wind.980139/
This is an endeavor to define the nature of "open/closed" systems, and, perhaps, to winkle out some of the semantic pitfalls I apparently waded into. I'll leave this open for a month or so to accumulate "folklore/anecdotes and wisdom/comments."

 

[Klystron]

While purchasing ingredients for vegetable soup from the grocery store, I carefully sealed each plastic bag by twisting and tying the open edges resulting in a minor air cushion. As the cashier was weighing each bag the bagger stuck her grubby fingers through the side of each bag realeasing the slight air cushion while loudly declaiming nonsense about seniors stealing from the grocer.

Nearly tongue-tied from this display of stupidity, bad manners and poor hygiene; I attempted to explain that the air in the bag of vegetables did not affect the scales. I tried to get the cashier and bagger to at least conduct an experiment and weigh the puffy bags before and after deflation. No go. Bagger was adamant that the slightly puffy bags would float, lighter-than-air like helium balloons, resulting in a lower scale reading. 'Pop!'

Bagger-girl fighting imagined crime one plastic bag at a time. What should you believe: your lying eyes showing no change on the scale after deflation; or some hare-brained crackpot 'theory' that a bag of vegetables weighs less when inflated with surrounding air?