Squirrels are really cool. They are human-like in that they have a level of curiosity and derring-do that seems, uh, greater than what you'd imagine evolution would select for.

We have a squirrel in our neighborhood that my wife and kids started leaving nuts out for. Within a few weeks, she would show up at the back door to wait for a handout. Now she has basically no fear of us. She'll take nuts from the kids' hands. She'll come right up to you, which is alarming if you're just trying to leave the house and don't actually have food on you. We have a Dutch door which we tend to leave open, and she's jumped onto the ledge before. It's probably only a matter of time before she comes all the way in the house, the cats notice, and all hell breaks loose.