The Adventures of Gumby: 1960's Series

Golden Iguana: Prickle wins a national pet contest and is awarded a prize golden iguana. The professor mixes a special formula for its food but there is one wrong ingredient. This causes the iguana to double its size. The blockheads decide to take the iguana but Gumby again manages to foil them. Before things are over though, the iguana gives them all a shock.