This teenage girl, growing up in a California coastal town, was obviously pregnant - stomach starting to swell, morning sickness, etc. She, however, tearfully insisted to her mother that she couldn't possibly be pregnant. She had never "done it" with a boy and it just wasn't possible.
As time went on, however, the signs continued. Her stomach continued to grow, her appetite increased, and so forth. Her mother insisted that she was pregnant. The girl insisted that it wasn't possible. She was still a "good" girl.
Finally x-rays were taken and the girl was vindicated. She had a large tumor in her stomach and surgery was performed immediately. To everyone's amazement the surgeons removed not a tumor but a small, live octopus that had fastened itself to the lining of the girl's stomach.
What happened to this girl is supposedly really possible. Octopus eggs are microscopic in size, and laid in clusters of tens of thousands. They are usually affixed to kelp at the ocean's bottom with a sticky secretion. It is not beyond the realm of possibility that a few could escape and float to the surface where they could be swallowed by an unsuspecting swimmer...
(Note: the above story is obviously not real. It is an urban legend found by me at www.snopes.com, and is categorized as false. Human biology cannot "give birth" to octopi, or, in story variants, frogs, snakes, lizards, fish or insects).