In the TV series Fargo, Malvo poses the question why people see more shades of green than any other colour and you'll know who I am. During the last episode Gus is waiting to kill him and says "I solved it". How?
Malvo first posed this riddle to Gus in episode 4, and later in that episode Molly gave Gus a clue ... she talked about how predators created a need in the prey to differentiate between shades of green so that the prey could protect themselves. So, when Gus hearkens back to this riddle in the finale, he's essentially telling Malvo he's figured out what sort of predatory nature Malvo has, and, in effect, realized that he must either kill the predator or fall prey to him.
Noah Hawley explained it in an interview with Yahoo TV.