Frog and the Treasure by Max Velthuijs
Frog and Little Bear go off to dig for treasure. 'But how do you know there will be treasure?' says Little Bear.'I just know,' says FrogSo together they dig a hole; a hole so deep that once they are in, they can't get out. Who will rescue them? And at the end of it all, will they have discovered treasure? Of course they will.