He couldn't help himself. Five minutes into Fox News Channel's GOP debate in Detroit on Thursday night, Donald Trump was already bragging about the size of his manhood. It was actually his second such joke of the day, having said earlier that Mitt Romney "would have dropped to his knees” if Trump commanded it.

In this case, he was responding to Sen. Marco Rubio's recent attack that Trump had tiny hands. (And you know what they say.)

"He hit my hands," Trump told a pulsating crowd at the Fox Theatre. "Look at those hands, are they small hands?” 

“If they’re small, something else must be small," he hinted. "But I guarantee you there’s no problem there, I guarantee you.”

“Alright, let's move on,” said Fox's Brett Baier to Trump's phallic boast, over nervous laughter from his co-moderators Megyn Kelly and Chris Wallace.

Trump Republican presidential candidate Donald Trump participates in a debate sponsored by Fox News at the Fox Theatre on March 3, 2016, in Detroit, Michigan. Voters in Michigan will go to the polls March 8 for the State's primary. Photo: Chip Somodevilla/Getty Images

They may have gotten past the anatomy lesson, but Trump's remark hung in the air. It set the tone for a debate that was raucous, nasty, and at times incomprehensible. Another jaw-dropping moment came in the middle, when Trump became so fed up with Rubio's interruptions that he rather unsubtly nicknamed him “Little Marco.”

“Alright let's hear it, Big Donald,” Rubio fired back. The audience was a wall of boos.

“Don't worry about it, Little Marco,” Trump thundered with a grimace. He went on bodyslamming Rubio and simply ignored Chris Wallace as the moderator attempted to ask a “policy question.”

“Gentlemen, you're – you're better than this,” Wallace stammered.

The crowd, of course, went wild. As is Trump's way, he once again let them know that in this election, anything is permissible. Call your rival “Little Marco.” Brag about your bulge. It's all good TV.

People expected a night of standoffs: between Trump and Megyn Kelly, which didn't really happen, and between Trump and his rivals Sen. Rubio and Cruz, which certainly did happen.

“Donald, please try not to interrupt,” said Cruz, losing his temper at his rival for walking all over his talking points. “Breathe. Just breathe.” Meanwhile, Rubio, still slamming Trump as a “con man” and a fraud, appeared to strain himself so much within the first ten minutes that his voice went hoarse for the rest of the evening.

But the greatest standoff was between the figures on the stage and the people in the crowd: The audience itself was so rowdy and so loud it acted as fifth candidate on the stage.

It was an audience of hecklers. They shouted freely at the candidates, at the moderators, and over each other. Each contender had their own frothy contingent of supporters that cheered for their man and unleashed hell whenever an opposing candidate launched an attack. The crowd's vocabulary went beyond applause and booing — people shouted their candidate's name, hollered encouraging words, and, when displeased, howled insults and attacks.

Trump has cultivated this type of atmosphere at his rallies; the other day, when he mentioned Hillary Clinton, someone in the crowd yelled, “She's a bitch.” But Thursday night's rumble normalized this type of behavior.

It was as if the Trump supporters in the audience infected the rest of the crowd, and, like some scene from “28 Days Later,” created a frothing red mass of bodies ready to lash out at anything and everything.

Fox's dream team of Kelly, Wallace and Baier had trouble getting out their questions. Wallace was booed not once but twice by the audience when he asked Trump about Mitt Romney's critical speech about him earlier in the day.

What went for the moderators went doubly for the candidates themselves. Rubio was jeered like a carnival freak as soon as he opened his mouth. Ted Cruz was booed by an ostensibly conservative audience for comparing Trump unfavorably to Ronald Reagan.

Even the avuncular John Kasich, who called himself the “adult in the room,” received rowdy cheers from his supporters as he gave his answers. During his closing statement, a Kasich fan yelped out something inaudible, sounding almost like he was in pain.

It raises the question of whether the media, even respected interrogators like Megyn Kelly, is going to be able to control this rodeo for much longer. CNBC was panned last year for letting its GOP debate go off the rails. When International Business Times interviewed the moderators at its competitor Fox Business, they needled CNBC and assured viewers that they would rein unruly candidates in with a buzzer.

That buzzer did nothing. Fox Business was scrambling just as hard as its rival to keep the event from dissolving into chaos. CNN hasn't been any better; Wolf Blitzer practically wilted before the candidates last time around. With every debate, the moderators — tasked with informing the public and extracting the truth from these candidates — appear more and more like they're simply trying to stay out of the crosshairs.

Like so many other aspects of this election cycle, the concept of a presidential debate has been Trumpified. And there may be no going back.

After Thursday's debate, some people at Fox were visibly shell-shocked. Take Bernard Goldberg, one of Bill O'Reilly's favorite guests and a supposed critic of “political correctness.” Grief-stricken over Trump's boast about his nether area, Goldberg appeared to miss a bit of the so-called “PC culture” he made a career of lampooning.

“Bill, I know you care about kids,” a shaken Goldberg said. “Imagine if a family was watching that, if a kid asked, 'what does that mean, Daddy?'”

O'Reilly, a career culture warrior, seemed unfazed and attempted to brush off the Trump remark. Goldberg persisted.

“Do you realize what he said?” Goldberg pleaded.

“I understand what he said,” O'Reilly said. “But this is a different time.”