This is NSFWish. But when I was a noob High School I was convinced by my girlfriend that girls "caberate" during puberty. (This was before the internet, mind you)

She made up this elaborate story because she didn't want to go to 'second base' with me yet. So, she came up with the story that she couldn't go to second base because she was caberating. I asked her what caberating was and she told me that it was a very personal and embarrassing time in a young girls life, and it was very difficult to deal with and to go through. For this reason girls did not talk about it with guys, and it was essentially a secret kept between females. Caberating, she explained to me, was a process that began after girls developed breasts. What happens is that all girls then slowly begin to develop new nipples. This process begins when the old nipples begin to shrivel, dry up, and fall off over time, like thick pieces of dead skin. Once the old nipples have dried up and withered away, new adult nipples begin to form and grow. She explained this process could take weeks to months. At the time she told me the story she said her niples were in the process of shriveling up and falling off. I was fucking horrified. I wanted nothing to do with whatever was going on under her shirt for a while. She also told all her friends to confirm this story, and because her best friend was dating my best friend we were both (my friend and I) duped by this story. Eventually she said the process had completed, but she never let me in on the secret until after the fact. Which she found very amusing.

I actually still talk to her today and we always have a good laugh over it.