Sitting on a ceramic chair sometimes you do not know what to do. In this regard, the Swiss urban planners installed atypical toilet cabins made of glass on the streets of Lausanne.

While the toilet is empty, any passer-by sees that inside it is cleanliness and comfort. Having entered inside and having closed a door glass becomes opaque, thereby giving a signal to another that the toilet is occupied.
This is where the fun begins. The visitor has the choice to sit in 4 walls, or press the "watch" button and watch what is happening around.

However, the "watch" button does not give a clear idea of who will be watching whom. The glass becomes opaque under the influence of current on the contained crystals, so it is not visible visually.
What did you do it for? There are 3 opinions. 1 - for fun. 2 - to study the behavior of people (who dare to be visible to all). 3 - to prevent negative cases, for example, the glass becomes transparent if there is no movement inside (a person lost consciousness), or very active actions (well, think here yourself).