I have one of those "universal tools," like a Leatherman.
Usually, it stays in my car, but some places I carry it in my pocket.
Has a knife, but also things like pliers and screwdrivers which I end up needing a lot more often than a knife. The ideal multitool has maybe only six or seven things on it. I don't think I've ever seen anyone use the corkscrew on a Swiss Army Knife.
When I was a kid, Scout knives were common, even in school. Why a Scout knife was sort of "okay" while switchblades were illegal still puzzles me a bit. Might have to do with the attitudes of the owners.