Fat as a Porpoise
The skin of the porpoise is nearly an inch thick, and under it
is a layer of fat somewhat thicker, and yielding oil of the finest
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Fat as a Porpoise from Fact Monster:
- porpoise - porpoise porpoise, small whale of the family Phocaenidae, allied to the dolphin. Porpoises, like ...