He met Butterly
Irreverent humor is part of the life-blood of Irish conversation, and sacred cows are not exempt—the country's remarkable piety notwithstanding. Ulysses is full of jokes in which sacred things become gently confused with trivial mundane ones.
In Telemachus, as Gifford notes, the biblical account of Peter’s recognition that he has denied Jesus three times—“And going forth, he wept bitterly” (Matthew 26:75)—begets Mulligan’s whimsical “And going forth he met Butterly.”
In Hades Bloom recalls another such joke, playing on Jesus' resuscitation of the dead Lazarus (John 11:43): “Come forth, Lazarus! And he came fifth and lost the job.”
Earlier in the same chapter, Ned Lambert tells Simon Dedalus that he has been down in Cork recently and seen a man that Simon knew there long ago. "And how is Dick, the solid man?" asks Simon jovially. "—Nothing between himself and heaven, Ned Lambert answered." Particularly since the men are standing in a cemetery, the reader may assume that Dick has died and gone to meet his Maker. But Simon knows the joke: "—By the holy Paul! Mr Dedalus said in subdued wonder. Dick Tivy bald?"
The best joke of this sort is told by the caretaker of the cemetery, John O'Connell, who asks the members of the funeral party if they have heard the one about the two drunks looking for the grave of a friend named Mulcahy: they find it and one reads out his name while the other is looking up at a statue of the Savior erected over the grave. “Not a bloody bit like the man, says he. That's not Mulcahy, says he, whoever done it.”