ROCHESTER, N.Y. -

Freshmen students at the University of Rochester may have had a terrifying start to their college career, courtesy of a prankster posing as their professor.

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The video has quickly gone viral, approaching seven million views in just four days.

The prankster -- a member of the "Chamber Boys" radio program at the university -- showed up a few minutes early with a briefcase. He erases the chalkboard, writes the name of the real professor and addresses the class.

"I'm Dr. Hafensteiner and I'll be your professor for Chemistry 131," he tells the class.

The fake professor -- whose real name is "Patrick" -- uses his limited time to terrify freshmen students on the first day of class.

"This class is extremely hard," Patrick says. "Last year, 55 percent of this class failed."

Patrick asks those interested in going to medical school to stand up. When the majority of the class stands up, Patrick uses a visual demonstration to once again frighten the optimistic students.

"I need everyone in the left-hand section and the middle section to sit down," Patrick says.

"Take a look at the portion still standing," he says with about a quarter of the students still standing. "That's the portion of the people who will actually make it to medical school."

His demonstration is met with gasps and shouts of disbelief from the first-year students.

The fake professor continues his scare tactics, telling students there will be strict consequences for students who bring laptops or cell phones to class. One by one, the video editors highlight students quickly hiding their laptops.

Finally, as the fake professor is about to start class, the real professor walks in.

"Who the hell are you?" the real professor asks.

When Patrick realizes the jig is up, he grabs his briefcase and runs out of lecture hall as students react with shock and laughter.

After taking control of his class, the real professor jokes about the prank just pulled on the class.

"At least he had the hairline down," he says. "That guy is not Dr. H. I'm Dr. H."