Let's say you take a trip out to your mailbox a few hundred yards away, and you know there are big packages in the box, and it's a downpour. So you grab an umbrella (knowing that true Oregonians never use umbrellas, but you make an exception for the sake of dry christmas presents). When you return to your front door with packages in hand, you place the soaking wet umbrella outside the front door to dry.
The next day, when you go out to a restaurant and it's been raining off an on, you take the umbrella, just in case, because you don't want the baby to get soaked while going to and from the car. The umbrella sits by your side for a couple hours while you eat. Then you head home, and on the way into the house, dump all the jackets and scarves and the umbrella on a chair.
Several hours later, around 11pm, you hear a ridiculously loud and strange noise, coming from the chair which is inside the house. The cats are confused. The sound comes and goes for the next ten minutes. It's natural, but also unnatural. It's not pleasant. It's quite loud, this sound coming from a chair in your house.
So here's the lesson: when you bundle your umbrella back up after it's been drying overnight, you might want to open it up and peek in real quick or you just might be carrying around a live tree frog for most of a day.