Peacock Feathers are Bad Luck
Peacocks may be attractive and impressive birds, but according to superstition, their feathers bring incredibly bad luck.
Because the markings on the end of peacock feathers resemble an eye, superstitious sorts believe this is a representation of the "evil eye", so bringing them into your house is extremely bad luck.
In the theatre, it is believed that having any sort of peacock feathers on stage (as a prop, as part of a costume or part of the scenery) brings bad luck. There are many stories of sets falling down and other performance disasters when peacock feathers have been on stage.