It all started with Biden’s participation in a rally about sexual assault and gender-based violence at the University of Miami on Tuesday.

The rally was hosted by It’s On Us, a movement started under President Obama to raise awareness about and fight sexual assault on college campuses. During the rally, Biden spoke in his typically candid fashion, suggesting that he would have “beat the hell out of” Trump were they still in high school.

Today’s @itsonus rally reminded us that we are responsible for creating an environment where sexual assault and gender-based violence is unacceptable. Thank you @joebiden for bringing us your legacy of ending violence against women and empowering our students to take action. pic.twitter.com/h43M4gqqpt

— University of Miami (@univmiami) March 20, 2018

The comment was made in reference to Trump’s alleged “grab them by the pussy” remarks. Biden took issue with Trump’s quasi apology, in which Trump called his comments “locker room talk.” Biden noted that, “They asked me would I like to debate this gentleman, and I said no. I said, ‘If I were in high school, I’d take him behind the gym and beat the hell out of him.’”

“I’ve been in a lot of locker rooms my whole life,” the 75-year-old continued. “I’m a pretty damn good athlete.” For good measure, he added, “Any guy that talked that way was usually the fattest, ugliest S.O.B. in the room.”

https://www.facebook.com/UniversityofMiami/videos/vb.17767109610/10155633704984611/?type=2&theater

Unsurprisingly, Trump did not take the criticism sitting down and chose his favorite mode of communication to share his feelings.

Thursday morning, Trump took to Twitter, writing, “Crazy Joe Biden is trying to act like a tough guy. Actually, he is weak, both mentally and physically, and yet he threatens me, for the second time, with physical assault. He doesn’t know me, but he would go down fast and hard, crying all the way. Don’t threaten people Joe!”

Crazy Joe Biden is trying to act like a tough guy. Actually, he is weak, both mentally and physically, and yet he threatens me, for the second time, with physical assault. He doesn’t know me, but he would go down fast and hard, crying all the way. Don’t threaten people Joe!

— Donald J. Trump (@realDonaldTrump) March 22, 2018

This isn’t the first time the two have come at each other. At a campaign rally for then-presidential candidate Hillary Clinton, Biden once again invoked the high school imagery, saying he wished he could take Trump “behind the gym.”

Around the same time, Trump responded, facetiously calling Biden “Mr. Tough Guy,” noting that he was only tough “when he’s standing behind a microphone by himself.”

And earlier this month, Trump lashed out at Biden at the Gridiron Club Dinner, calling Biden “Sleepy Joe!” and (erroneously) referencing the “behind the barn” comments he made. Trump told attendees, “Trust me, I would kick his ass. He’d be easy.”

“Joe, gimme a break,” Trump continued. “A guy who keeps making outrageous statements thinks he has a shot of being president?” Trump’s comment is in reference to speculation that Biden will seek the Democratic nomination for president in 2020.