the journal you keep... what kind and where do you hide it

we've started keeping a little notebook of meets and adventures, just for us, who we met, what worked, what we'd do differently, and ive realised pretty quickly that this is sensitive material that absolutely cannot end up in front of family... so the question is two parts really — does anyone else keep one and find it useful or is this oversharing into a book. and where the hell do you hide a notebook in a normal house where curious teenagers and cleaners and the dog walker all wander about. ive thought of locked drawer but that screams "i have a secret"... open to clever ideas