The grey go away bird (Corythaixoides concolor) is a relative of the cuckcoo from South Africa. The bird is called a go away bird because its distress call sounds somewhat like the words "go away". In the wild they eat mostly fruits and insects, but at certain times of the year will move to a diet that consists mostly of flower petals. It is not unknown for large mobs of them to get together and harass birds of prey, and even occasionally large carnivorous mammals. They are the least colorful of the turacos which often have vibrant plumage and interesting markings. I've met a really friendly, very likable grey go away bird, so I find that I am fond of them. Turacos generally strike me as fairly clever and kind of under appreciated birds. There is also a mystery grey go away bird living in Arizona at Gilbert ranch called the "Gilbert bird". It is odd as it is illegal to export the grey go away bird from south Africa and they are very, very rare in captivity in the US. This one is also unbanded suggesting it was not an escaped captive bred individual, so it might be very lost.
Here is the "go away" call It is at the bottom of the page