What they found on the Internet were references to a business that Pennsylvania corporation records show he helps run - SwingFest Events.
Its website advertises conventions for improving one's sex life and features sexually suggestive photos and information.
Jean could not be reached for comment.
Upper Dublin School District Superintendent Michael Pladus said Friday that "arrangements were made through the high school to bring in a speaker with an antidrug and alcohol message.
"We are in the process of investigating what occurred."
A senior who was in the audience on Thursday and asked not to be named said, "At first, it was just, this guy was an awful public speaker."
But then, the student said, the stories got "ridiculous."
Another student who was there said Friday that he and his friends heard no advice, not even a theme, amid Jean's wild tales. Instead, he told the kind of life details that are better left unsaid.
"He was talking well over the hour and a half we were there, everything from how he was drafted by the Phillies at age 16 to how he drank a case of beer when he was 14," junior Matthew Rosenstein said Friday.
One Web-savvy student took a screen shot of a website on which Jean was accused of unsavory activities, and posted it on the photo-sharing website Instagram, the senior said.
"I thought it was really humiliating for the school overall that a bunch of teenagers with phones were able to run better background checks on this guy than the administration," the senior said.
By the end of the day, Schultz had sent parents a message:
"While assemblies and speakers are often quickly forgotten, a strong reminder was served today that careful vetting is a must, and I assure you that it will not happen again."
Matthew Rosenstein's mother, Jill, said she wasn't upset about Jean, although she did wonder why school administrators didn't stop his speech long before 90 minutes had elapsed.
"I kind of thought it was funny that the school would allow this to happen," she said. "I know my kid's not going to do these things."