Question

MONTRESOR: My dear Fortunato, you are luckily met. How remarkably well you are looking to-day! But I have received a pipe of what passes for Amontillado, and I have my doubts.

FORTUNATO: How? Amontillado? A pipe? Impossible! And in the middle of the carnival!
MONTRESOR: I have my doubts, and I was silly enough to pay the full Amontillado price without consulting you in the matter. You were not to be found, and I was fearful of losing a bargain.
FORTUNATO: Amontillado!
MONTRESOR: I have my doubts.
FORTUNATO: Amontillado!
MONTRESOR: And I must satisfy them.
FORTUNATO: Amontillado!
MONTRESOR: As you are engaged, I am on my way to Luchesi. If any one has a critical turn, it is he. He will tell me—
FORTUNATO: Luchesi cannot tell Amontillado from Sherry.
MONTRESOR: And yet some fools will have it that his taste is a match for your own.
FORTUNATO: Come, let us go.
MONTRESOR: Whither?
FORTUNATO: To your vaults.

Answer 1

Fortunato excitedly says "Come, let us go" because he is looking forward to tasting the Amontillado, unaware that it is a trap.

Step-by-step explanation:

Montresor seems to bring up the cask of amontillado to pique Fortunato's interest because he knows Fortunato is a fan of wine. By purposefully mentioning that he supposedly bought this wine, Montresor cleverly builds hype. When he mentions it and seems to go on about something else, it only leaves Fortunato to become more and more excited at the thought of tasting the wine.

It's all apart of Montresor's plan, he mentions the wine and makes it seem as though it was all Fortunato's idea to go down into the cellar where he will inevitably become trapped and die. Also, Fortunato saying "come, let us go" excitedly further characterizes him as a little bit ditzy and extroverted. Hope this helps!