What is a pobblebonk, and why is it called that?

Limnodynastes dumerilii is a frog species native to Australia. They call it pobblebonk because it has a distinctive call that sounds a bit like a banjo being plucked. That is why they also sometimes call it Banjo frog! Perhaps that is why pictures and statues of frogs with banjos are fairly common. This word I got from an interview I heard with Dr Roly Sussex from the University of Queensland