It depends.
When the VGA socket I’m plugging the VGA cable has a screwing hole (for example, tower PCs as well as some HDMI-To-VGA adapters) , and I’m intending to let it plugged, I generally do screw them in, not entirely, but sufficiently to don’t let it escape due to VGA cable’s weight (especially if the cable has dozens of meters as well as those cilindrical magnetic thingies that reduces electromagnetic interference).
But one of my laptops have no screwing holes at the sides of the VGA socket so it’s impossible to screw the VGA cable.
As a Brazilian, not much. Throughout my entire lifetime, I saw some Brazilians there and there wearing Halloween costumes but it’s not as popular here as “quermesses” (kirmess, church fairs, happening mostly on Brazilian’s interiorian towns), Carnival, Christmas or some “important” soccer game (such as Corinthians vs Palmeiras, or Flamengo vs Fluminense).
To me, particularly, no holiday (nor soccer games) holds any importance or meaning. In the end of the day, it’ll be just capitalism mesmerizing people to spend money on temporary things.