This can totally happen by accident as it happened to me two nights ago and that's how I ended up in this site. My guy and I were alternating between the caramel and capitan positions, we where both very wet and while doing it he hit my anus just hard enough that I felt the worst possible pain I ever had. I couldn't even speak and started to crawl out of bed slowly in agony. Now, I'm much older then my guy who's only 20 but have had enough experience to know that this was an accident and not intentional. His average erection is 8.5'' long and no less then 6'' wide and even though it was just the tip that penetrated I was bleeding. He was very worried and apologized many times and I'm still recovering.