When Stanley slouches into the Wreck Room later, X-Ray is animated and talking loudly. Stanley joins Squid on the couch and as X-Ray shouts, Zigzag grouses for X-Ray to be quiet so he can watch TV. Stanley is perplexed and a little worried; Zigzag is staring intently at the broken television.
When compared to the other boys' exhaustion, X-Ray's behavior shows just how mentally, emotionally, and physically difficult digging is. It reinforces how cruel the camp is, as it clearly deprives the boys of their humanity.
The next morning, the Warden walks Group D to the holes again. Stanley spends most of the day dumping wheelbarrows and thinks a lot about the tube. He thinks it looks familiar and wonders if it's the lid of a fancy gold pen. The Warden starts getting impatient by lunchtime and even tells Mr. Sir that if the boys don't dig faster, he'll have to dig with them. After this, the boys work extremely fast and Stanley almost runs with his wheelbarrow, especially when Mr. Sir is around. He reminds them they're not Girl Scouts. They're the last group in that afternoon.
When Group D is the last group in, it shows again that the Warden makes the rules at Camp Green Lake and can break them just as easily: making them keep digging shows her breaking the contract of sorts between the adults and the inmates and reinforces her power. Her threat to Mr. Sir shows too that she can and will weaponize absolutely anything to get what she wants.
Later, Stanley wonders if there's a way he could tell the Warden where the tube actually came from. As he's turning it over, Mr. Pendanski comes into the Wreck Room with a letter for Stanley. Squid gives Stanley a hard time about receiving a letter from Stanley's mother, but X-Ray suggests the letter is probably from Stanley's girlfriend. Stanley waits to read it until later. His mother writes that Stanley's letter made her feel like a parent who can afford to send her kid to summer camp. She also explains that while Stanley's father is close to a breakthrough with his sneaker project, the landlord is threatening to evict them because of the smell. She makes a joke about feeling sorry for the little old lady who lived in a shoe.
X-Ray's suggestion that the letter came from a girlfriend suggests that the inmates at camp may actually be more willing to look out for each other than the novel has thus far let on. Note, however, that X-Ray's suggestion does indicate that he's been listening to Mr. Sir's refrain about the Girl Scouts. It's likely that Mr. Sir would deem a letter from one's mother girly, while a letter from one's girlfriend connotes masculinity and power.
Zero startles Stanley asking him what's funny. Stanley initially refuses to tell Zero what Stanley's mother wrote, but eventually gives a basic explanation of Stanley's father's project and his mom's joke. Zero seems to not recognize the reference to the nursery rhyme about the little old lady who lived in a shoe, which amazes Stanley. Zero asks Stanley to recite it, but Stanley just goes to dinner.
Stanley's reaction here shows that, at this point, he's pretty unwilling to think about people's experiences that are very different from his own, which Zero's lack of familiarity with the nursery rhyme suggests. When Stanley simply leaves, it also implies that he's becoming less interested in others.