galgo98,
I shooed them out of the bathroom before they discovered that there is water in the toilet. They did enjoy playing "echo chamber" with the waste basket.
They'd stick their heads in the basket, call, take their heads out of the basket, call, stick their heads in the basket, call, and on and on and on. It was as if they simply enjoyed experimenting with acoustics.
I have seen them do this a number of times - they seem to use sound to explore cubbie-hole type places like gaps between straw bales, or wood piles, or hollow trees.