The first suggestion of humor in "The Cask of Amontillado" occurs when Fortunato makes his first appearance dressed, ironically, as a court jester--a fool.
The man wore motley. He had on a tight-fitting parti-striped dress, and his head was surmounted by the conical cap and bells. I was so pleased to see him that I thought I should never have done wringing his hand.
When Montresor suggests that he should seek out their mutual friend, Luchesi, as a participant instead, Fortunato replies,
"Luchesi cannot tell Amontillado from Sherry."
"And yet some fools will have it that his taste is a match for your own."
Fortunato's cough is of concern to Montresor, and he recommends that the two men go back. But Fortunato must sample the sherry.
"Enough," he said; "the cough's a mere nothing; it will not kill me. I shall not die of a cough."
"True—true," I replied...
Montresor, of course, already knows Fortunato's fate. Montresor mocks Fortunato when he makes a toast "to your long life." Another amusing moment occurs when Fortunato asks for a sign that Montresor is also a membership of the fellowship of Masons: Montresor produces a trowel, the tool of trade for masonry. "You jest," Fortunato tells Montresor, but he will soon see that the last laugh is on him.