My wife is so paranoid about someone finding the toy stash she me made buy a safe for them! Well, it's one of those lockable steel record storage boxes with a combo lock on top. It actually works too well. It is such a pain to get in to in the heat of the moment that the go-to toys are in the nightstand anyway (wrapped in a paper towel, in a ziplock bag, under other junk).
I think the paranoia started when she dreamed about her parents finding her toys. They never go upstairs and never pry, so that is highly unlikely, but I understand how disturbing a dream like that can be. I can't say I blame her for being paranoid regardless of her dream; one of our three kids in particular is a snoop and I can just see our 5 year old grandson running out of our room, new discovery in hand, demanding to know what it is!