I just randomly heard a loud "dry" gurgling coming from my upstairs shower drain. It was draining slowly (assuming due to all the hair from a house full of females) so we have been using the basement shower. This particular shower hasn't been used in months. I haven't used the toilet or sink in this bathroom in about 2 hours and then I hear this weird sound. Is it possible to hear it from the clogged pipe hours after I used any other bathroom appliance?
If the shower has not been used for a long time, the water in the P-trap under the drain will evaporate, so you no longer have a seal against the sewer lines. So anything else that drains into the sewer will make sound that can now come back through that shower drain. That by the way would also be letting sewer gasses back into your house, which is not good. Pour some water into that shower and see if the sound goes away.
Sounds like a sewage issue in the drains..if it continues you may find sewage backing up into a lower drain area. Under a heavy load the water can litterally suck the toilet bowl dry. Rent a snake and send down the drain to clear clog or try some drain cleaner. A house full of women 1 might have flushed something that should not have been flushed