Razor blades in the walls....

Kylie Klein Nixon Reporter from Homed

Has anyone ever seen something like the image below in an older Kiwi home? Does anyone remember them from their childhood? These strange slots allowed you to rid yourself of an old razor and never think of it again...but it also meant, years down the track, that someone renovating would be in for a nasty, rusty surprise.
I'm certain I've seen something like this here in Aotearoa-NZ, but can't for the life of me recall where. It was in the back of the medicine cupboard. Let us know if you've seen, had - or have - one in your home.