Part 1:
Joseph marries Mary, who was a little girl at the time. He tries to consummate his mariage, and though he does break her hymen, he cannot satisfactorily penetrate her VAGINA because his PENIS is too big (and Mary is too young). Because he cannot fuck her VAGINA, he decides to have anal and oral sex with her.
Part 2:
One or two years passes, Joseph continues to have anal and oral sex with Mary. Mary becomes very good at giving blowjob/receiving deep-throats. Joseph ends up not even caring about VAGINAl sex. The deep-throats are very impressive due to Joseph's huge PENIS.
Part 3:
Mary meets a young boy, older than her by 1 or 2 years (right after waking up, still half dreaming and thinking about it, I ended up considering that the shota should be a Greek boy, for some reason. I think it's supposed to indicate that he's a kid from a family of foreign origin that's important in the region... Even though it's really the Romans that were ruling things up in Judea during the Ist century BC). While flirting, Mary impresses the boy with her oral sex skills. Because the boy has a boy-sized PENIS, he can have VAGINAl sex with her, and he does.
Part 4:
Mary became pregnant from that sexual encounter. She explains it to Joseph by telling that it must have been Yihood (YHWH spelled funnily (by me) to make fun of the jews and imply that they were polytheists before their exile @ Babylon (see the Elephantine papyri)) that must have put a child in her because Joseph's PENIS is too big for that. She says that without really thinking that it's going to convince Joseph, trying to technically not be lying by saying that the child is Yihood's willing. However, Joseph is convinced, because he is a very religious man. He cannot verify that she had sex with someone else, because he broke her hymen the first and last time he tried to have VAGINAl-sex with her (the whole hymen story is a rationalization I made after waking up).
Part 5:
With time, Mary shifts her lie into being that the child she's bearing isn't only the child of she and her husband, but directly the child of Yihood. Joseph believes her because he is a very prideful/vain man.
During my dream, the whole "YHWH pronounced Yihood" thing was a way to invoke plausible deniability about the story, saying that it isn't actually a story of how the Virgin Mary became pregnant, but just a story about some girl named Mary. It does help that I didn't remember what's Joseph's name.