When I was in third grade, I found out what menstration was from an episode of "Blossom." I didn't totally understand it, so my older sister Amy explained it to me in full. Blood and tampons and all that.
For some reason or another, I felt that this had tainted me. Like I had knowledge of some horrible thing.
Later that night, when my mom came home, I embraced her as soon as she walked through the door. I said, "Mom, Amy... told... me..." and then I broke down into tears.
Fortunately, my mom forgave me.
.... I'm so Catholic.