I live in a college house by a city, so every now and then I get a little worried about someone breaking in. Was having some trouble sleeping one night (inconveniently before a test) so I was lying in bed around 2:30 am, and I start to hear this faint, intermittent scratching on my bedroom door. I'm already a little freaked out because it sounded like what my cat at home growing up would do, but we don't have any pets. A minute or two later, I hear one of my roommates scrambling into the bathroom, and now I'm just frozen in bed. Thankfully, he asks if anyone is up out loud, so I ruled out an intruder and reply. Turns out there was a bat flying around in our house (for the second time!). Ended up staying up til 4 am to catch it.