It's crazily inaccurate, from everything I've read and learned about the female reproductive system. NoChowder, you and other men don't ever have to worry about this happening. The womb--or at least the only part of them that comes in contact with the penis, the cervix--doesn't open to admit penises. It will just barely accommodate microscopic sperm cells and the fluid they travel in through a tiny opening. The only time a woman's womb opens up is when late-term pregnancy hormones kick in and the cervix opens to let a baby out. But truly that's it. It's tightly, structurally closed for a reason--to prevent infection and preserve the part of the body that is designed for carrying babies.

Admittedly, this makes for a very dramatic and engaging story. And perhaps the normal uterine contractions with orgasm made the lady who started this thread truly believe that was happening. But wombs don't admit penises. It's physically impossible. Do some anatomy research, and you'll see this is true.