He was having a senior moment.
President Biden joked that he could not remember his name moments before he donned a red Donald Trump hat during a 9/11 commemoration event Wednesday.
Biden, 81, made the crack at his own expense when he agreed to sign a presidential seal hat for a Trump supporter at an event honoring first responders in Shanksville, Pa., video footage shared on TikTok showed.
“Do you remember your name?” the Trump fan — an older man in suspenders — asked Biden.
“I don’t remember my name,” the octogenarian commander-in-chief replied, earning laughs from the crowd.
“I’m slow,” he added.
“You’re an old fart,” the Trump supporter agreed, to which Biden responded, “I’m an old guy.”
“I know you would know about that,” the president fired back at the jokester, who insisted that he himself was still a “young timer.”
Biden bowed out of the presidential election on July 21, in the wake of a disastrous debate against former President Trump that left loyal supporters and high-ranking Democrats questioning his mental fitness.
“He reminds me of the guys I grew up with. There was always one in the neighborhood,” Biden told the crowd of the opinionated interlocutor.
The man offered to sign his Trump hat for Biden, but the president quickly shot down the offer.
“Hell, no,” he said before briefly placing the Trump hat over the baseball cap he was already wearing.
“I’m proud of you now, you old fart,” the Trump supporter told Biden of the quick stunt.
Biden then cautioned the crowd against “eating cats and dogs” — referring to Trump and JD Vance’s largely debunked claims that migrants have been eating household pets in a small Ohio town.
The Trump fan, however, argued that the pets tasted “good,” like “Kentucky Fried Chicken.”
The woman who first posted the video on TikTok, who claimed to be the Trump supporter’s granddaughter, did not immediately respond to The Post’s request for a comment on the interaction.
The footage of Biden bantering with the man and trying on the Trump hat quickly made the rounds online.
The White House called the gesture a display of “bipartisan unity” in honor of the somber 9/11 anniversary — but most commenters were quick to carry on with the joke.
“I’m Joe Message and I approve this Biden,” newsletter writer Craig Chamberlin replied on X, seemingly playing to the ongoing gag about Biden’s alleged senility.
“Biden has a lucid moment,” another user wrote.
One person posted a meme of Biden with a Trump hat edited onto his head in a photo of himself with former President Barack Obama.
“Joe going on a comedy tour when he leaves office,” the self-proclaimed “most conservative dog on X” chimed in.