That happened to me one time. We used lube we never used before. I had the head of my cock pressed against her hole. I shifted forward to position myself to enter her slowly but the head popped in and slid deep inside. Caught me by surprise how fast it happened. She yelped and yelled too fast. Afterwards, she told me I really hurt her and caused a little bleeding. I felt so bad. Never used that stuff again and made sure to be extra careful. Now, years later I know what it's like to be entered too quickly and can appreciate how she felt.