The Law of Demeter (“talk only to your friends”) is a good place to start, but think about it this way: you can play with your toys, with toys that you make, and with toys that someone gives you. You don't ever, ever play with your toy’s toys.
Source: The Thoughtworks Anthology
What could the last sentence mean? Could a toy have a toy? Assuming a toy means "A toy is an item that is used in play", a toy can never have a toy, so one cannot play with a toy’s toys (it's physically not possible).
The context is object oriented programming.