By the time they enter grade school, most children know 30 to 40 taboo words, according to Dr. Timothy Jay, a psychology professor at Massachusetts College of Liberal Arts who has extensively studied swearing and linguistics.

"What Would You Do?" explores people's attitudes toward juvenile profanity in a scenario in which a 6-year-old actress drops the f-bomb at a New York City bakery.

Watch one woman's surprising reaction below, and see the whole scenario on "What Would You Do?: Child's Play" Friday at 9 p.m. ET.

What's the worst language you've ever heard a child use? Share your story below!