Well, light switches actually.
These aren’t my switches, but they look cooler so I thought I’d use this picture rather than show you the boring white ones that probably look a lot like the ones you already have on your wall.
But picture the ones on your wall. The ones you use everyday. The ones you probably pay no attention to…until one day. Until the day you notice that one of the screws isn’t in all the way.
Perhaps it’s due, as your husband says, to normal wear and jostling — years of the plate being pushed, ever so slightly, up and down. Or, more likely, it’s because someone tampered with the wiring.
Did they flip it so off is on and on is off as a practical joke? Did they disconnect it totally so as to not work when someone sneaks in later that night? Did they plant a bug? Did they hide jewels or drugs in the light switch box?
Why would your character find the light plate only partially screwed in?