Sliders

This is a photo of the instructions posted on the inside of a sliding restroom stall door in the Takamatsu airport.

Believe it or not, the (not-pictured Step 2 of the) instructions were actually useful because the lock was like some sort of logic puzzle where you have to figure out the exact direction and angle at which two pieces of metal engage and disengage.

While conceptually a good idea to save space in those tiny airport restrooms (when was the last time you saw a stall as big as the one in the diagram?), this door proved more novelty than useful.