How indeed? Unnoticed by Piper, she is telling a joke that Siv has heard before, from Zane - slightly off-color, but still safe to tell to your parents - though maybe not a conservative grandmama.
"And he said, llama? No, that's my WIFE!" Both moms laugh, though Vera rolls her eyes upward a bit. "How is Zane doing? We really must have another McCormick family get together, call in all the cousins and relations."