Oh wow… flashback time. (no pun intended)
I hit on the idea of using an empty cassette case, as well. But, having “cool” parents was a royal pain in the ass, as between them they listened to most of the same music I did, which made my rack of tapes a dubious hiding place at best.
Until it occurred to me that I wasn’t restricted to buying tapes that I absolutely loved. So I bought an Anthrax tape, tossed the actual tape itself in a cardboard box full of blanks, and used the case as a stash.
I figured (rightly enough, as it turned out) that would be the one tape neither of my parents would ever get the urge to listen to.
And as a bonus, for about three months, I was hooked on the I am the Man psuedo-rap, to boot. See what bad things drugs can do to you, kiddies?