This may not be a quote, and might not the the most appropriate, but this has to have happened to everyone a few times in their life. Those times when you wake up in the morning and you get a sudden urge to pee... You run to the bathroom and after you're done you look over and well ^ that happens. It is just a funny way of reminding people to change the toilet paper rolls. Or a better luck next time precaution.
Life Lesson: Always check the toilet paper before you sit down on the toilet :)