Many years ago, I worked in a call center. I was sitting with someone who was new helping them take calls and both of our headsets were plugged into the phone. The trainee was helping a store employee and she was just being awful to him. While she went to get something from the customer, I muted the line and said, "God, what a bitch!" except my finger was hovering over the button and I hit it just in time for her to hear me say bitch. I fully panicked and hung up on her. Nobody ever said anything to either of us and this was back when landlines would occasionally cross, so hopefully she thought that's what happened since she hadn't heard my voice up until then.

Anyway, I'm pretty sure that's the origin of why I still don't trust mute or hold to this day. I'm not talking shit until I know that call is disconnected.