When you work in an industry everybody uses, you learn a lot of information the general public doesn’t know. Retail employees learn all the weird ways people try to shoplift; those in food service learn exactly what goes into our meals, and those who work in aviation learn a lot of information about passengers, planes, and what happens to your luggage in the cargo hold.
The top-rated answer was from a flight attendant who advised passengers to count the number of rows back to the closest exit. In a real emergency situation, there is a pretty good chance it will be difficult to see. By counting each seatback as they pass, passengers can quickly find their way to the exit even if vision is impaired.
One user shared information gained from a flight attendant that, if passengers are told to brace for impact, they should place one hand over the other—not interlace fingers. The top hand will protect the bottom hand from injury during impact. If possible, place the dominant hand beneath.
And then things got fun.
One user informed everybody that tray tables are rarely sanitized. So, do not put food directly on the tray table.
Another user talked about what happens when aircraft transport cadavers or body parts for hospitals. Surprise ending: sometimes the carriers leak onto luggage.