I was on the phone a couple weeks ago making reservations for our cruise in February. The lady helping me was very nice but she kept hesitating and I could tell something was wrong. Finally she asked me if I heard the same echo that she was hearing. I told her that I didn't and offered to call her back. She said that we were almost through so it wouldn't be necessary.
It was a couple minutes later when I realized that my shadow (Sadie) was sitting right next to me mimicking my every move. She had her held tilted to hold her imaginary phone, her legs were crossed and she was pretending to write down the reservation information. That's when I realized that the "echo" was Sadie. Not only was she copying my every move but she was repeating every single word that I said. I hadn't even noticed!
After I explained the "echo" to the customer service rep, all three of us had a good laugh. Sadie's giggle was of course another echo!