THIS IS WHY WE LOVE THE MOB! JOHN GOTTI JR. LOSES IT IN COURT & SCREAMS TO A MOB RAT I'LL KILL YOU!

And on the seventh day, he lost it.
An enraged John A. (Junior) Gotti exploded Thursday, fed up after a week's worth of damning testimony from his ex-best friend - reportedly threatening to murder the mob informant in a Manhattan courtroom.

"I'll kill you," Gotti mouthed at John Alite just before the once inseparable duo shared a high-decibel Mafia meltdown in front of a stunned audience.

Jurors didn't see Gotti send that silent message to Alite, and they were ushered out of the courtroom before the real fireworks minutes later.

As Alite stepped down from the witness stand, he slowed and snarled at Gotti.

"You got something to say to me?" the star government witness barked, later telling the judge about the threat.

"You fag!" Gotti shouted back. "Did I kill little girls? You're a punk. You're a dog. You're a dog. You always were a dog your whole life, you punk dog."

The ugly encounter in federal court came after Alite blamed one of Gotti's uncles for a murder in the early 1990s.

The testimony enraged Gotti, who shouted at Alite while court officers intervened.

"You want to strangle little girls in a motel?" Gotti screamed as Alite was led away. "You dog!"

Alite had just testified that Vincent Gotti had strangled a young woman in a drug-fueled fight and left her body in a Queens motel bathtub.

Defense lawyer Charles Carnesi suggested Alite was the real killer.

"Ridiculous," said Alite, laughing. "His uncle, yes, strangled somebody and killed her. ... I wasn't there."

Alite confirmed that Junior was later blamed for the slaying, infuriating the Gambino boss.

Gotti, 45, facing his fourth racketeering trial, apologized for mouthing off, but federal Judge Kevin Castel was not moved by the mea culpa and said another outburst would land him in contempt.

"You are not doing yourself any favors, and you violated my direction," said Castel, who had warned Gotti during jury selection to keep his mouth shut.

Castel said he did not see Gotti mouth the threat at Alite, but accepted Prosecutor Elie Honig's claim that a U.S. Marshal saw Gotti do it.

"He lipped to me, 'We're gonna kill you,'" Alite told the judge. "So I said, 'What?' And he said, 'We're gonna kill you.'"

Gotti's mother, Victoria, said Alite went after her son because Carnesi was getting too close to the truth. Carnesi had forced Alite to recount hundreds of lies he had made - to the government, lawyers, family and friends - as he tried to worm his way out of a life sentence.

"Alite is a pathological liar - a rat caught in a proverbial trap, caught in his own lies, and he lashed out," she said.

The ex-friends ignored one another when they returned to court later in the day.