The incident, Jao reported, occurred about 9:40 p.m. on Friday, Sept. 28, near Penn's graduate school of education building, at 37th and Walnut Streets.
"We felt horrible," Jao said in an interview Monday. "It was really, really disgusting."
Jao and her friends reported the incident to Penn campus police, who have investigated but have been unable to identify the culprits. There is no proof they were Drexel students, or students at all, or that they were involved in a sorority or fraternity, officials said.
"It certainly sounds like perhaps a rushing for a fraternity or sorority prank. It was unsettling for sure," said Maureen S. Rush, vice president for public safety. "But even if they were caught, we're not sure we would have been able to charge anybody as a criminal justice matter."
The actions as described did not appear to constitute indecent assault, she said. More than likely, Jao and her friends would have been given the offenders' names and told that they could pursue a private criminal complaint for harassment, Rush said. The offenders, if students, also would have been turned over to the school's student conduct office, which could require community service or take other sanctions.
Rush has not heard of a similar case at Penn in her 18 years there, she said.
Drexel is in contact with Penn police to learn more about the incident, but officials there said it appeared unlikely the perpetrators were from Drexel.
"Since we are on a quarter system, [late September] was the first weekend back to classes for our students," Drexel spokeswoman Niki Gianakaris said. "Drexel fraternities/sororities don't host recruitment events until mid-October."
Jao wrote an opinion piece about the incident that appeared in the Daily Pennsylvanian, Penn's student newspaper, on Thursday.
"It was horribly dehumanizing," wrote Jao, 27, a graduate student in Penn's secondary education program and a student teacher at Northeast High School in Philadelphia. "All of us felt like we had been treated like animals, like convenient pieces to be picked up as a part of a collection. Asians are not Pokémon to be collected."
The group told Jao and her friends that they could win a $300 prize if they completed the task, she wrote.
"After that, things happened fast," she wrote. "Without asking for our permission, the group tried to separate my friends and me from each other. One woman had a camera. There was a flash. During this time we heard reassurances. Shouts: 'Don't worry, we need to take pictures as proof, but it doesn't have to be real.' "
When one of the men tried to kiss her, she said, she forced his arm away and said: "No, we're not doing this. No."
The group argued for a bit, then left Jao and her friends, she said.
Jao's two friends, a male and female, are international students and do not want to be identified, Jao said. Also graduate students, they are on student visas and do not feel comfortable going public, she said.
Jao, who is from Michigan and whose parents came to the United States from Taiwan, said she decided to make her case public so students would know to report such incidents to police without hesitation.
At first, she and her friends were confused, she said. That's why they waited three days to report the incident.
"As a teacher, I felt I had the responsibility to push this forward," she said. "In the future if anything like this happens, they will not hesitate to go to the police. They will not wonder is it that bad? Because yes, it is that bad."
Jao praised Penn staff and public safety for their reaction and help.
"Penn's been overwhelmingly supportive," she said.
Contact Susan Snyder at 215-854-4693 or firstname.lastname@example.org, or follow on Twitter @ssnyderinq.