At a school in the USA, the girls in their early teens had just discovered lipstick.
They would go into the female toilets to apply it.
Then, giggling, they’d leave imprints of their lips on the large mirror.
This made a lot of extra work for the cleaning staff.
The head teacher asked the girls to stop.
Of course, they ignored her.
So she took the girls to the toilets for a demonstration.
She said, ‘It takes a lot of work to clean the lipstick off the mirror.’
She said to the janitor, ‘Please show the girls how much work it takes.’
The janitor put the mop in the toilet, squeezed off the excess water and washed the mirror.
Then put the mop in the toilet again, and repeated the process. From that day on there was no more lipstick on the mirror.
That’s choice architecture.