They really do respond to and understand humour! I've seen them intelligently reply to human jokes and enjoy "one up" verbal jousting. A good example is Cosmo the funny parrot on KZbin, who likes to insist that she has hair and Mummy has feathers. She gets a real kick out of it😂 And they don't show humour when they're neglected, afraid or in a negative atmosphere. It seems, similarly to humans, humour emerges only when the parrot is happy and feels secure and loved❤