I'm going to show you a picture of my apartment's half bathroom, and you tell me if you see a spot absolutely no one would ever possibly find over 20 diapers via casual snooping. First one who guesses it is the winner and gets a reputation point for being elite.
Think of yourself as the ultimate diaper watch patrol. Where are those diapers hidden?
Hint - There is nothing tricky about this bathroom, it is just like any regular residential half bathroom that you've been in.