The Democratic vice presidential nominee took on the role of stern teacher, telling Trump to "not treat my Joe like that. He's a nice boy."
"Kamala, I got this," Biden replied, to which she quipped, "Joe, let Mamala go to work." After forcing Trump to apologize, Harris gave musical guest Megan Thee Stallion and Cardi B's song "WAP" a whole new meaning.
"I think if there's one thing we learned tonight, it's that America needs a WAP: Woman as President," she stated as the crowd cheered. "But for now, I'll settle for HVPIC: Hot Vice President in Charge."
"So why don't the two of you finish this debate or whatever the hell this is with dignity? And when you're done, I've got you boys some PB and J and apple slices waiting for you," she said, walking off stage.
Just last week, Rudolph told ET that she considers it an "honor" to play Harris. The actress has portrayed the politician since SNL's 45th season premiere last year, and she's hoping she'll get to continue to play her for years to come.
"It's really such an honor to be involved in any presidential race, and this one is a real doozy. So it is really an honor," Rudolph said of playing the California senator. "I got to meet her, and she is so fantastic. She is so incredible, she is so energizing and I just feel so good to be associated with someone so positive."
"I just want to do her proud -- just do a good job, no pressure!" she added. Rudolph won an Emmy last month for her SNL impression of Harris, though she's still not convinced she's "nailed it." Hear more in the video below.
SNL airs Saturdays, live coast-to-coast at 11:30 p.m. ET, 8:30 p.m. PT on NBC.