A disinterested defendant busted for a threatened shooting spree in upstate Woodstock yawned and doodled Friday as he entered a guilty plea at a bizarre Brooklyn hearing.

William Swift, 33, acknowledged his interstate transmission of threats to injure with the menacing messages spurred by an anti-vegan grudge that led him to detail plans of a mass shooting and stabbing rampage at the Woodstock Fruit Festival last August, authorities charged.

“I don’t believe there are any competence issues at this juncture,” said defense attorney Nora Hirozowa, who acknowledged those issues “play a role in the underlying offense.”

The Brooklyn man also stretched and appeared to discuss a pen with his lawyer, prompting the judge to ask the defendant to focus. Officials said Swift made threats to multiple people between February and June of last year.

Federal officials said the self-described “involuntary celibate” sent threatening e-mails and audio recordings to an organizer of the Woodstock Fruit Festival, including one where he threatened to “do a f---ing Ted Bundy” on the woman.

In another chilling message, he mentioned specifically targeting “the Jewish meet-up ... The would be ideal,” prosecutors said. The event was billed as a “vegan health retreat.”

“I have been going to see psychologists, psychiatrists, shrinks since I was 7 years old,” Swift told Brooklyn Federal Magistrate Judge Sanket Bulsara at the sentencing. “I don’t keep track of what they say I have. I don’t care.”

The judge said he did care, so he “can get the appropriate help.”

When Bulsara asked about Swift’s time in the Manhattan Detention complex since his August arrest, he responded, “Just short of seven months now. I’m having a great time.”

An additional charge of interstate stalking will be dismissed at his sentencing, officials said.

According to prosecutors, the campaign of threats began in February 2022 and only escalated from there. He threatened to “go to Woodstock with a gun” and to stab people “with my legal pocket knife.”

The one-time East New York resident told the judge about his time behind bars following his arrest by the FBI, who tracked all the messages to an internet address at his home.

“I was in the hospital before I was arrested,” said Swift at at the hearing. “I read that in the news about me. ... I sent threats with the intent to harm, to cause bodily harm to innocent people. E-mails and I guess phone, too.”

Swift was arrested by the NYPD last July in a separate case after an Instagram message to a friend detailed his fantasy about “shooting up Washington Square Park,” according to a criminal complaint.

A text message to the same friend detailed his fears of impending arrest.

“I’m afraid the FBI is going to get me,” he wrote. “I’ve threatened so many people when I’m drunk. I’m scared I can’t fix the damage I’ve already done.”