This thread makes for some interesting reading! just amazing how creative people can get, but also a little sad I think, as some have said before, sex is the most natural thing and not something you should hide and be embarrassed about... anyways.
I always used to (and in fact still do) fall into the scatterers camp. Even if one hiding place would have been discovered, it means only one thing being found rather than a big pile of paraphernalia. I now only live with my OH so no need to hide stuff, I am simply still in the habit of keeping different toys in different drawers etc.
When I was still living at home, my collection was admittedly much smaller than these days and it was quite easy to stash away. I would have one or two things in my art, craft and sewing stuff boxes underneath odd bits of fabric, paints, balls of yarn (even inside a ball of yarn works with smaller toys) and such, then some smaller items in my toiletry bags zip compartments or wrapped in small plastic bags, the sort you get from boots/similar or in a bit of loo roll - cosmetics bags always seem to be full of odd bits and I tend to wrap shampoos and such in bags anyway to make sure they don't leak everywhere. Another favourite place of mine was in one of my "memories" boxes, I had a few boxes of old letters, leaflets and tickets from events I'd been to, old drawings, seashells and trinkets and such random bits, basically things no one would ever need to borrow and would not be of much interest for anyone either - but also something others could not "organise" or throw away as it was important stuff for me.
My family always used to be pretty respectful of privacy, but as mentioned before, every now and then someone might simply want to borrow non-personal stuff like a handbag which makes it a not-so-good hiding place. (Great when moving house though, as someone pointed out before. if a box is opened and full of handbags and shoes it's not particularly urgent and so you can just say you'd like to organise them as you unpack yourself. equally a few boxes/toys hidden underneath and between books in a big box - just say you have a method for how you want to organise your books on the shelves so they would help the most if they just left the box alone so you can do it the proper way first time round, when you have time later on.) Relatively "plain sight" and of no interest or use to others just always seemed to me the most logical way of hiding anything, even christmas pressies and all. In case you have a mum or sister who loves to borrow your make-up / toiletries - say that you would appreciate them not to do so, as you have read about all the infections you can get from sharing and are a bit irrationally worried about that happening, even though you don't actually believe in them giving you anything you just wish they can respect you being slightly neurotic about it ;) or if you have a mum who would reorganise your wardrobe/desk/room when you're away, again say you feel very particular as to which way you want your things to be arranged and her "helping" is counterproductive as you don't see it as a nice treat but instead you then have to immediately fix it when you get back and thank for the gesture but just ask not to do it.
I now keep about half of my toys in their storage pouches in a few underwear drawers, simply because it's a nice soft place where they don't get squished and are easy to get to, and another half in the bedside cabinet. Lubes are in the same cabinet, as well as some on the bedside table, plus I have covered a few old shoe and LH boxes with pretty wrapping paper to keep my "naughty clothes" in (one for corsets, one for socks and suspender belts etc) The flat's been in a bit of a state recently in general, there seems to be some toy overspill on the bedside tables and bathroom too :) just wonderful not to have to hide stuff and worry about it anymore. we did joke about hanging a recently purchased butt plug with a finger loop handle on one of the bathroom towel hooks next time someone comes to visit, just to see their reaction!
The parents-questioning-locked-containers issue had me thinking though - if you have younger siblings, especially girls, then surely a toiletry / make-up case with a lock should be the easiest thing in the world to justify, as you wouldn't want the young ones to play with your make-up and ruin it! Alternatively, if you are a non-make-upping lady or a male, then take up a hobby that involves expensive, potentially dangerous or delicate stuff - like painting miniatures, they are easy to break and younger kids will surely spill the paints and make a mess of everything! a lot of fine art paints are expensive and can be an irritant and palette knives are sharp, let alone craft knives, pins and nails... you get the idea. as long as the box that needs to be locked (for others' safety or to keep the items inside safe) is big enough to have other stuff underneath :)