That's an odd situation. Maybe you were in a hurry and the clock was in your hand while you were near her backpack, and it accidentally slipped inside. It could have been a small alarm clock or a pocket watch.
I'm not entirely sure what you mean by 'cooking slipped in her casserole'. It could be a very unique or accidental situation. Maybe you were trying to transfer some cooked ingredients into the casserole dish and it accidentally slipped in an unexpected way.
Well, perhaps it refers to an object or an event. Say, a small memory or an item that unexpectedly found its way into the story about his wife while he was telling it. It might be something like a little joke that he didn't plan on saying but just came out as part of the story.
It could mean he secretly introduced something (like an idea or a small object) into the stories about your wife. Maybe he added a false detail or a new element without permission.
Since I don't have direct knowledge of this novel, it might be about a complex relationship where boundaries are crossed in some way. It could explore themes like friendship, trust, and the blurring of personal spaces. For example, perhaps there is a situation where one friend becomes so involved in the other's life that it's like they are 'slipping inside' their world, seeing things from their perspective in a very intense way.
I'm sorry, but I don't know who the author of this novel is. There are so many novels out there, and without more information, it's hard to determine the author.
For instance, he was recounting a story of their vacation. He was focused on how his wife loved the beach. But then, accidentally, he slipped in that she got a little scared when she saw a big crab. So, the incident of her getting scared by the crab was the 'it' that found its way into the story about his wife.
First, you should find out exactly what 'it' is. If it's something inappropriate or false, you can calmly correct the person and set the record straight.
First, make sure your neighbor is okay physically. Then, depending on what your wife's story is about, you might need to clarify things. If it's a misunderstanding, calmly explain the real situation to your neighbor.