Andy Gross, who has been silent since the incident, did not respond to requests for comment

What should have been a fun performance capping off Purdue University's freshman orientation took a dark turn after comedian Andy Gross appeared to sexually harass a student onstage, in front of an audience of more than 5,000.

Gross made a female student touch his thigh as part of his routine, joked about his genitals and made the audience so uncomfortable that thousands of students left in protest, according to several students and video footage from the event.

In response, school officials denounced Gross amid calls for a boycott.

"Some portions of the performance were clearly inappropriate and contrary to the university's values of respect and support for all," the school said in a statement. "We will not work with this comedian again and are proud of our students who are standing up and voicing their concerns about the performance."

It all started when Gross forced a female student - a supervisor with Boiler Gold Rush, the group running the orientation - to volunteer for a trick, according to several students present at the performance. Gross singled out the student by asking her to raise her hand, then thanked her for volunteering and pulled her onto the stage.

While doing a card trick, Gross - a Los Angeles comedian whose act includes magic and ventriloquy - repeatedly asked the girl to come closer to him. As they stood back to back, Gross joked about being "cheek to cheek" and "feeling her vibrations," Ryan Grunsten, a Purdue freshman who was in the audience, told The Washington Post.

"He made her stand closer and closer to him and made a joke about that giving him a erection and making his pants seem to say 'let me out,' referring to his genitals," said another student, Andora Fess, according to the Indianapolis Star.

Then, Gross asked the girl to touch his thigh. From the display screens that showed a close-up of the performance, multiple students said the girl looked like she was on the brink of tears and touched Gross as little as possible, despite his nagging.

As Gross flubbed a guess-the-card trick, he quipped: "Well, I got a free feel out of it."

The student stood silently, staring at the floor, video footage reveals.

Then, she left the stage and began to sob, according to Cara Pietrangelo, a junior and BGR supervisor. Other students rushed to comfort her.

"She felt like she was kind of abused," Pietrangelo told The Post. "She was harassed sexually and put in a situation in front of people where she didn't know what to do."

Gross, who has been silent since the incident, did not respond to requests for comment from The Post.

Following the performance, students took to Twitter to slam Gross - hashtag #AndyGrossIsGross - and to call for Jimmy Fallon to keep the comedian off of "The Tonight Show."

To the students' horror, the humiliating card trick was just the beginning. Things got even more disturbing as the act progressed, witnesses said.

Gross singled out another female student and chided her when she refused to come onstage. After a trick involving a dove, he flipped off the audience, saying, "I got another bird for you," according to students who saw the performance.

Later, Gross had a male student sit on his lap and pretend to be a puppet as part of a ventriloquist act.

Before the performance was halfway through, most of the audience had walked out. Freshmen streamed out of the auditorium and onto the lawn, where they shared embraces. In GroupMe messages, they tried to process what had happened.

Numerous students were distressed and crying, according to Marisabel Segovia, another BGR supervisor.

"We had witnessed firsthand a sexual assault; that's not something that's easy to see," Segovia said. "We were wiping our tears and then going ahead and helping students. We didn't want them to have to go through this right before class starts."

Gross's behavior was even more jarring because of what preceded it.

Before he took the stage, one student had shared her story of campus sexual assault.

"Last night, I shared my experience with sexual assault in front of 7000 new students at Purdue," Paulina Karbowski tweeted. "Moments later, I watched my friend get sexually harrassed by Andy Gross on the same stage. Now, I can't wait to watch us end his career."

Grunsten, one of the freshman who'd tweeted about the ugliness of Gross's performance, said he was comforted by the campus community's response.

"It's disgusting that it happened at all, but I guess you could see some silver lining in how the community reacted to it," Grunsten said. "People did bounce back from this."