Jimmy Johnson (no relation) was a young boy who owned a bizarre pet, the Grockle, a creature resembling a cross between a dragon and a dog. Their adventures were chronicled in the early years of the Dandy.
Jimmy's uncle had found the Grockle as a large egg while visiting South America, and posted it to his nephew as a present. To warm and hatch the egg, Jimmy placed it in the oven, and when the bizarre creature emerged, it made a repeated "grockle" noise. Despite its unusual appearance, Jimmy befriended the newborn animal, finding that it would voraciously eat almost anything, and it rapidly grew until it was bigger than him. When he took it for its first walk outside, it defended him from local bully Big Bill Brown, and afterwards Jimmy dubbed it the Grockle, after the noise it made.