Thank you ClaCla_The_BBRaeFan, this is hard because I've seen a lot of strange things in the 14 years of my life.
I would have to say that walking in on my parents having sex when I was 4 years old, I remember walking in, wanting to ask mom something, I walked in and then dad yelled at me to get out. I ran out of there. Never will I walk in without knocking first again.