This event helps situate the comedy...
In act 1 of Oscar Wilde's play The Importance of Being Earnest, Algernon Moncrief's best friend, Ernest Worthing, is the owner of a soon-to-be-infamous engraved cigarette case. The case makes its appearance after Ernest accidentally leaves the object behind at Algernon's house.
This event helps situate the comedy because the cigarette case, which Ernest assures Algernon is "his" (Ernest's) cigarette case, is engraved with the message,
From little Cecily, with her fondest love to her dear Uncle Jack.
Algernon is now aware that his friend Ernest must be leading a double life. However, in his sarcastic, "Wildean" fashion, Algernon plays a game of questions and answers in order to compel his friend to confess the truth.
But why does your aunt call you her uncle? . . . There is no objection, I admit, to an aunt being a small aunt, but why an aunt, no matter what her size may be, should call her own nephew her uncle, I can't quite make out. Besides, your name isn't Jack at all; it is Ernest.
In typical Wilde style, the phrases, axioms, and paradoxes in the dialogue make a regular conversation turn quite humorous. It all ends with the confession by Ernest that he is " 'Ernest' in the city, and 'Jack' in the country," which fascinates Algernon—a fellow "double lifer."
The tea scene occurs shortly after the cigarette case event.
Lady Bracknell, the ultra snobbish aunt of Algernon, had been invited to tea. This very sophisticated ceremony would have included her favorite cucumber sandwiches.
However, prior to the the cigarette case discovery, Algernon and Ernest/Jack had been helping themselves to the cucumber sandwiches, bread, and butter that had been specifically set aside for Lady Bracknell and her daughter, Gwendolen.
When the time comes to start tea, Algernon and his butler, Lane, concoct the lie that there were no cucumbers in the market, not even for "ready money." This is followed by yet another humorous exchange of paradoxes and ironies that also help situate the comedy. After all, tea ceremonies are expected to run without flaws in upper class societies. What Algernon and Jack did was not only selfish, but a total social faux pas. Wilde, the king of comedies of manners, uses dialogue to twist the situation and make it laughable.
[Algernon.] I am greatly distressed, Aunt Augusta, about there being
no cucumbers, not even for ready money.
[Lady Bracknell.] It really makes no matter, Algernon. I had some
crumpets with Lady Harbury, who seems to me to be living entirely
for pleasure now.
[Algernon.] I hear her hair has turned quite gold from grief.
Notice how the tea ceremony, and the lack of the fancy cucumber sandwiches, moves the conversation away from the social faux pas and into the ironic transformation of this Lady Harbury, whose state of grief has left her mysteriously hedonistic, even going back to having youthful blond hair, after her husband dies. Irony and sarcasm in dialogues are staples in Wilde's comedies.