Pip tells Pumblechook and Mrs. Joe the following lies about what happened with Miss Havisham at Satis House:
1) Mrs. Havisham is “very tall and dark”
2) She was sitting in a black velvet coach eating cake and wine on gold plates
3) She had four “immense” dogs that “fought for veal-cutlets out of a silver basket”
4) Pip and Estella played with flags (Estella’s was red and Pip’s was blue)
5) They play with swords (Ch. 9)
All of these things are fanciful and ridiculous. They come from a child's imagination of what a rich lady might be, and have no connection with anything that actually went on at Satis House.
Why then, did Pip lie? He felt that he could not explain what happened there.
I felt convinced that if I described Miss Havisham's as my eyes had seen it, I should not be understood. Not only that, but I felt convinced that Miss Havisham too would not be understood …(Ch. 9)
When Pip goes to Miss Havisham’s house, it is a confusing and disturbing experience for him. When he is confronted by Uncle Pumblechook and Mrs. Joe, things get even worse. He does not know what to say to them, because on the one hand he does not think they will believe him, and on the other hand telling the truth just seems like a bad idea. It will make Miss Havisham seem odd, and his time there is his own. He can’t tell them the truth, so he makes up stories that are fanciful and just unbelievable enough to be believable.
When Joe questions him later, Pip breaks down and admits that it was all a lie. Joe reaches for some element of truth in it. (“But at least there was dogs, Pip”?) But Pip admits that there was nothing.
Pip does not tell them the truth because his loyalties are already beginning to shift.
[Although] she was perfectly incomprehensible to me I entertained an impression that there would be something coarse and treacherous in my dragging her as she really was (to say nothing of Miss Estella) before the contemplation of Mrs. Joe. (Ch. 9)
He was enchanted, by Miss Havisham and by Estella. He does not want to open that experience up to scrutiny. There is more here than meets the eye. He is not ready to let his regular family know about them. In that house he saw a glimpse of himself, and he did not like it. He does not want to be coarse and common. He wants to be worthy of Estella. Miss Havisham already has her hooks in him.