OMG.....What is that noise???

It's late at night and I'm surfing the Internet......in the dark. There is no noise but the sound of the ceiling fan when I hear this slosh, slosh , slosh sound. What is that noise and where is it coming from? And there is Doc hanging over the toilet drinking. I don't think (at least I never caught her before) doing this. She has a food and water dish. What makes the toilet so special? Anyway......I thought it was a funny picture and a very weird thing for Doc to do. Steve said from now on all seats are DOWN!!!

BTW.......just in case you needed to know....it was clean water :)