My mom had just gotten new hearing aids at the same time I was dogsitting for a friend. Since I wouldn't be home all weekend I asked her to feed and care for my pigs while I was away. (They have their own room across from mine on the second floor) When I came home everything was good with the guinea pigs but my mom was complaining that she thought her new hearing aids didn't work right. When I asked her why she told me "well I keep hearing these weird sounds at night, like whistling or birds chirping. but it sounds like it's inside the house. I guess I have to go back to the doctor even though I can hear everything else just fine."
By this point I had started laughing uncontrollably. My guinea pigs love to chirp very loudly at night :)