The fourth paragraph of E.A. Poe's "The Cask of Amontillado" tells of when Montresor comes upon Fortunato. It is evening and carnival season. Carnival is celebrated during the season of Lent, and people celebrate by eating and drinking to excess. They also wear masks and costumes to both hide their real identity and be able to act as another person. In the case of the story, Montresor comes upon a drunk Fortunato. Fortunato is very friendly to Montresor. Fortunato is dressed as a jester, something which Montresor finds approproate. His costume is striped and tight, with a comical hat and bells sitting atop his head.
The action of this paragraph depicts the meeting of Fortunato and Montersor. Fortunato's drunken state and jester's costume make Montresor pleased. One can assume that Montresor means to make a joke of Fortunato, and his (Fortunato's) drunken state insures that enacting his revenge may not be as difficult as he (Montresor) may have thought.