Why is my teacher so mad at me?

A couple and I were hanging out at my house after school about a week ago and we were playing truth or dare. When it came to my turn I picked dare expecting them to ask me something totally nonsensical and out of the question. However, all they told me to do was ejaculate onto a piece of paper for them to keep. I thought this seemed like a lucky day for me, so I did it right away, considering myself fortunate for not getting something as ridiculous as spinning around 50 times. Anyway, by the time I finished and released my semen onto the paper, my friends laughed deliriously for about five minutes and then left, saying they were only joking. Bewildered, I left the paper on my coffee table face-down so that my parents wouldn't see the stain of **** on the other side and forgot about it. A few days later, I picked up a random piece of paper and did my Spanish homework on it. The next day as I took it out of my folder to show the teacher I realized it was the same paper from the truth or dare game. When my teacher saw it, she was shocked and became very angry and said "what is this?!". I shrugged and told her calmly it was my semen. Everyone in the class stopped talking and stared at my desk with mixed expressions of surprise and embarrassment. After a moment of awkward silence, I grinned and said "I guess I have to work on my aim, huh?". At that point, the teacher sent me to the main office and I told the principal what happened to said that he would call my parents into a conference on Sunday. What I don't get is why my teacher responded like that. My mothers think it's ridiculous that they have to leave their service on a holy day (they're both nuns), and I totally agree with them. I was thinking I could maybe talk to my teacher privately and prove to her that I was telling the truth by performing the act again where she could observe the color and smell up close but I realized she always has a class and wouldn't be able to find any time. Can anyone explain to me what's wrong with this and why I'm being penalized for being human?