Mark Twain's use of similes in the text heightens the humor found in the piece as well as adds to the Local Color aspects of the story. For instance, when describing Jim Smiley's dog, Andrew Jackson, Twain writes that when the betting was getting serious, the dog's "underjaw'd begin to stick out like the fo'castle of a steamboat." Twain, who takes his name from steamboat and boating terminology, uses a simile that places this story with the adventurers of the Mississippi and West. The "forecastle" of a steamboat is the portion of the boat that sticks out in the front and was used for storage of things like the anchor or stage planks. Twain uses another simile in the same sentence describing Andrew Jackson that also relates to steamboat terminology: "his teeth would uncover, and shine savage like the furnaces." The furnaces were used to boil the water that created the steam.

Another way Twain uses similes is to create humorous imagery. The second of Smiley's animals that Twain describes in detail is Dan'l (Daniel) Webster. When describing the "jumping frog of Calaveras County," he writes, "you'd see that frog whirling in the air like a doughnut—see him turn one summerset, or may be a couple, if he got a good start, and come down flat-footed and all right, like a cat." When one thinks about a frog jumping, he or she imagines a simple jump up and down, but Twain's similes create a more humorous image of that frog. All of Smiley's betting animals did not look or act as one would think, like the mare that had asthma, but the fact that they all could win bets for Smiley adds to the disbelief created in this story, thus adding to the humor.