A childhood belief about bathrooms

Growing up, my family's bathroom was all in pink, as was the style at the time. And every once in a while, I would find a piece of pink toilet paper floating in the bowl with a darker red circle on it. I thought it had something to do with the pink dye turning red in this pattern when it got wet. So little scientist that I was, I would drop hundreds of sheets of toilet paper into the bowl, one by one, and watch to see if the red circle would manifest when the ink got wet.

I forgot all about that at some point. Years later, coming home from college, I observed my mother walk into the (no longer pink) bathroom, put on her lipstick, grab a sheet of toilet paper and blot her lips on it. Voila! Mystery solved. Red lipstick on pink toilet paper.