I hadn't thought much about that aspect. Geocaching (which I'm also involved in) would lend itself toward teaching you a lot about hiding things in plain sight.

Some Geocaches are right out in the open. There's one near my house that I know I walked right past hundreds of times before I got into Geocaching and discovered it. Had it not been for seeing it listed online, with GPS coordinates (and even a hint), I'd have never guessed it was there.

Some of them are ammo can-sized or even larger, but these are generally not hidden where they'd be found easily or freak someone out. Most of the plain sight ones are very small, I've found one that was about as big around as a pencil and maybe 1" long.