In The Adventures of Tom Sawyer, superstitions are important because people feel that with these beliefs they have control over certain situations. The children feel empowered by superstitions, especially if these notions seem to prove true.
One superstition that Tom holds is his cure for warts. In chapter 6, Tom runs into Huckleberry Finn. Among other things, they discuss ways to remove warts. When Huck claims that dead cats are effective, Tom asserts that he has a better method; namely, using spunk-water. According to Tom, the person goes alone to the middle of the woods, where there is "a spunk-water stump." When midnight comes, the person with the wart on his hand backs up to the stump and jams his hand inside while saying,
Barley-corn, Barley-corn, injun-meal shorts,
Spunk-water, spunk-water, swaller these warts. (Ch.6)
Then, the person walks away swiftly, going eleven paces with his eyes closed; after this, he turns around three times. After doing these things, he walks home without talking to anyone. "If you speak to anyone, the charm's busted," Tom warns. After listening to Tom, Huck says that this method is not the one that Bob Tanner has. Tom, however, gives Bob Tanner no credibility because he claims that Bob is "the wartiest boy in this town."
In chapter 9, Tom and Sid say their prayers and climb into bed. Tom waits for Huck to come by so that they can go to the graveyard and test Huck's theory about dead cats' ability to remove warts. As Tom waits anxiously, the old beams in the house seem to "crack mysteriously" and "the stairs also creak." Then a cricket begins its annoying chirping that no person could locate.
Next the ghastly ticking of a deathwatch in the wall at the bed's head made Tom shudder—it meant that somebody's days were numbered. (Ch.9)
Later Tom is undoubtedly convinced of this superstition because he sneaks out of the house when Huck Finn comes by, and they go as planned to the graveyard. There they witness the robbing of a grave for Doctor Robinson. Injun Joe is digging there with Muff Potter. When Joe wants more money for their nefarious deed, the doctor knocks Joe to the ground and wrestles with Muff, who is struck in the head with the dead man's headboard. While the two men are on the ground, Injun Joe picks up Muff's knife and kills the doctor with it. Joe then places the knife in Muff's hand. When Muff regains consciousness, Joe acts as though Muff has killed Doctor Robinson. Because Muff is a drunkard, he believes Joe; he begs Injun Joe to not tell anyone, and Joe agrees gladly. Unknown to Joe, however, is the fact that the boys have witnessed all this.