Tea is very much a staple in Ulysses. In the first episode, in Martello Tower, Stephen Dedalus, Buck Mulligan, and Haines are having breakfast, which includes tea. The anecdote Mulligan tells is a tale that is often retold by readers of Ulysses. The "Mary Ann" referred to is a character in an anonymously Irish bawdy song.

"Buck Mulligan, hewing thick slices from the loaf, said in an old
woman's wheedling voice:

-- When I makes tea I makes tea, as old mother Grogan said. And
when I makes water I makes water.

-- By Jove, it is tea, Haines said.
Buck Mulligan went on hewing and wheedling:

-- SO I DO, MRS CAHILL, says she. BEGOB, MA'AM, says Mrs Cahill,
GOD SEND YOU DON'T MAKE THEM IN THE ONE POT.

He lunged towards his messmates in turn a thick slice of bread,
impaled on his knife.

-- That's folk, he said very earnestly, for your book, Haines. Five
lines of text and ten pages of notes about the folk and the fishgods
of Dundrum. Printed by the weird sisters in the year of the big
wind.

He turned to Stephen and asked in a fine puzzled voice, lifting his
brows:

-- Can you recall, brother, is mother Grogan's tea and water pot
spoken of in the Mabinogion or is it in the Upanishads?

-- I doubt it, said Stephen gravely.

-- Do you now? Buck Mulligan said in the same tone. Your reasons,
pray?

-- I fancy, Stephen said as he ate, it did not exist in or out of the
Mabinogion. Mother Grogan was, one imagines, a kinswoman of
Mary Ann.

Buck Mulligan's face smiled with delight.

-- Charming! he said in a finical sweet voice, showing his whiteteeth and blinking his eyes pleasantly. Do you think she was? Quite charming!

Then, suddenly overclouding all his features, he growled in a hoarsened rasping voice as he hewed again vigorously at the loaf:

-- FOR OLD MARY ANN SHE DOESN'T CARE A DAMN. BUT,
HISING UP HER PETTICOATS ..."