Coma
There's a woman in a hospital in a coma. Her nurse notices after a few days that every time she sponge bathes the woman around the crotch, her vital signs, according to the nearby monitor, increase significantly.

The nurse gets the bright idea that oral sex might just provide the stimulus to bring the woman out of her coma. She calls the woman's husband, tells him her idea about oral sex, and he agrees.

When he arrives at the hospital, the nurse ushers him into the room, closes the curtain around the bed, and closes the door. Five minutes later, the man comes running out of the room screaming that all of his wife's vital signs have plummeted to zero and she needs a doctor immediately.

The nurse, upset that her idea had not only not worked, but seemed to be threatening the life of the woman she had sought to save, asked the man what had happened.

"I'm not sure, but I think she choked".