These guys always make me chuckle. The first time I encountered a grey go-away bird – which is very common all over southern Africa – I was working in the back yard and was startled by its sound, which at the time sounded like a child saying “heeyyyyy…” from about 10 feet away. They will answer when you call back using their sound – “kweehhhh” (or “go-away”). This is what a group sounds like: kwehhh