Karyn had heard rumors that Biff had knocked up and abandoned several girls in school. So she decided to give Biff a fitting punishment.
"I wish that until I wish otherwise, that Biff Meadows was an unwed mother. He would have a woman's reproductive system and be pregnant with a baby. He would get the same amount of sympathy and support as the girls that he knocked up and would raise his children by himself. Finally, he would ultimately have the same number of children as he had fathered on other girls."
The stone flashed and, across town, a very pregnant Biff began having problems of his own.