In my lifetime Halloween has mutated from a holiday for (mostly) kids to a national event for everyone. The first time I noticed this was in the late 1980s when I worked at Apple. The Halloween tradition there was for everyone in costume to march around the campus in a long line, parading down Bandley Drive in Cupertino and ducking through the lobbies and interiors of each building. That was pretty fun.
At Microsoft in the '90s, at least once or twice, employees' kids came to campus and went trick-or-treating from office to office.
What happens where you work?