Time for more classic puzzles!
There is an island whose only inhabitants are perfectly logical monks with strange practices. Every monk has either red eyes or brown eyes. Red eyes are considered a curse, and any monk who discovers that he has red eyes must kill himself next time it is midnight.
However, the monks do not have any way to discover if they have red eyes. There are no reflective surfaces on the island. While monks can see each other's eyes, they have taken a vow of silence and are not allowed to communicate with each other.
One day, a tourist came by and loudly noted that at least one monk on the island had red eyes. At first, all the monks just silently regarded this fact, but many nights later there were a bunch of suicides. What happened and how?
Bonus question: How do the writers of these puzzles come up with such disturbing situations?
See the solution