if i had any irl i would put them beside my japanese mangas where nobody looks, other than that on my laptop, in a folder where all my other H related stuffs are kept.
Well I don't have any doujins, but my gf does have a pretty big collection. She don't have to hide it, it's on a shelf. She lives by herself in an apartment.
I hide mine (because my extended family visits often with their kids ) inside a secret temple guarded by deviosly hard puzzles and traps that can only be accessed with the crest of Hyrule. but not really. i hide them in a hidden shelf in my bedroom that nobody knows about.
all over the house... i.e Under my mattress, In bookshlves blending in with my manga colection, on my desk covered with lot's of paper stuff(I told them before not to touch my desk), there's one at our living room I think... camouflaging himself with the books...