President Biden briefly put on a red Trump hat Wednesday during a visit to a fire station in Shanksville, Pa., where he was ruthlessly ridiculed by one of the former president’s supporters. 

As the president mingled with first responders after marking the 23rd anniversary of the Sept. 11, 2001, terrorist attacks, it appears he offered to trade one of his hats for the Trump supporter’s cap, video posted by TikTok user shows. 

“I’ll give you my presidential hat,” Biden told the man, noting the “presidential seal on it.” 

The Trump supporter, an older gentleman wearing “Punisher” suspenders, insisted that Biden sign the hat to seal the deal, and the president agreed.  

“Do you remember your name?” the Trump supporter quipped. 

“I don’t remember my name,” the 81-year-old president responded. “I’m slow.”

“You’re an old fart,” the Trump backer said, forcing Biden to acknowledge, “I’m an old guy.”

“You’re an old fart, right?” the man continued, openly mocking the president.  

“I know you would know about that,” Biden shot back at the balding man, who then claimed to be a “young timer.” 

The bizarre back-and-forth didn’t end there. 

“He reminds me of the guys I grew up with,” Biden said as he finished signing the presidential hat. “There was always one in the neighborhood.”

When the president asked the supporter of the GOP nominee for his red Trump hat, the man asked, “You want my autograph?” 

“Hell no,” Biden replied.  

At the crowd’s urging, Biden proceeded to briefly place the “Trump 2024” hat over the hat already on his head. 

“I’m proud of you now, you old fart,” the Trump supporter told Biden. 

“Just remember, no eating dogs and cats,” the president said as he made his way away from the Trump backer, who strangely argued, “They’re good,”  likening the taste of family pets to “Kentucky Fried Chicken.” 

Footage of Biden, 81, donning the hat was quickly shared by the Trump-Vance campaign and the White House later confirmed that the president had tried on the headwear in the spirit of bipartisanship.

“At the Shanksville Fire Station, @POTUS spoke about the country’s bipartisan unity after 9/11 and said we needed to get back to that,” White House senior deputy press secretary Andrew Bates wrote on X.

“As a gesture, he gave a hat to a Trump supporter who then said that in the same spirit, POTUS should put on his Trump cap. He briefly wore it.”

Supporters of the Republican nominee were less magnanimous.

“Kamala did so bad in last night’s debate, Joe Biden just put on a Trump hat,” the Trump War Room account posted on X along with footage that appeared to be reversed to show Biden putting on the hat rather than removing it.

Earlier, Biden had brought beer and pizza to the firehouse after participating in a wreath-laying ceremony at the memorial to United Airlines Flight 93, which was taken down by Al Qaeda hijackers with 40 people on board on that tragic day more than two decades ago.

Passengers on the Boeing 757 had stormed the cockpit before the terrorists could crash the jet into its intended target, believed to be either the White House or the US Capitol building.

Shanksville is located in Somerset County, a heavily Republican area where more than 77% of voters backed Trump in the 2020 election.

Ironically, during Tuesday night’s debate with Vice President Kamala Harris, Trump mused about sending the Democratic nominee one of his trademark red ‘Make America Great Again’ hats while needling her for poaching his ideas.

“Everything that she believed three years ago and four years ago is out the window. She’s going to my philosophy now,” Trump said. 

“In fact, I was going to send her a ‘MAGA’ hat. She’s going to my philosophy.” 

Biden, who dropped out of the 2024 race July 21, had long accused Trump of posing a threat to the foundation of the country. 

“Too much of what’s happening in our country today is not normal,” the president said during remarks in September 2022. “Donald Trump and the MAGA Republicans represent an extremism that threatens the very foundations of our republic.”

The Post contacted the White House for additional comment.