She told him that her husband had developed a penchant for anal sex, and she was not sure that it was such a good idea.
"Do you enjoy it?" the doctor asked. "Actually, yes, I do" she said. ''Does it hurt you", he asked? "No. I rather like it!" ''Well, then," the doctor continued, "there's no reason that you shouldn't practice anal sex, if that's what you like, so long as you take care not to get pregnant."
The woman was mystified. "What? You can get pregnant from anal sex?" "Of course", the doctor replied. "Where do you think Gordon Campbell came from?"