Donald Trump's predictable unpredictability

"Mr. Trump should get back on his meds."
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"Mr. Trump should get back on his meds." 04:30

(CNN)If there's one thing that's predictable about Donald Trump, it's his unpredictability.

The bombastic real estate mogul was surprisingly reserved at this week's Republican presidential debate. His demeanor was in stark contrast from past debates when Trump delighted in ridiculing Rand Paul's hair and mocked comedian Rosie O'Donnell.
But just as the political world was beginning to wonder whether Trump was done with the theatrics, Trump delivered his most sensational speech yet. At a campaign rally in Fort Dodge, Iowa, Thursday night, the businessman let loose a winding and furious 95-minute tirade that was, at times, jaw-dropping -- even by Trump's standards.
The candidate started by mocking Carson's descriptions of his violent outbursts as a youth. Trump zeroed in on the neurosurgeon's claim that he once tried to stab an acquaintance, only to have the knife break on the person's belt buckle.
    Stepping out from behind the podium to give the audience an unobstructed view, Trump pointed at his own belt.
    "So, I have a belt. Somebody hits me with a belt. It's going in because the belt moves this way! It moves this way! It moves that way!" Trump yelled, flipping over his buckle several times. "He hit the belt buckle. Anybody have a knife? Want to try it on me? Believe me, It ain't gonna work!"
    The rant came hours after he told CNN's Erin Burnett that Carson's self-described "pathological temper" was comparable to the traits of a child molester.
    Trump's performance was yet another reminder that his rivals have no way of knowing when and how the GOP front-runner will suddenly come after them. From mocking their physical appearance to reading our their cell phone number on national television to pure name-calling, no tactic is off limits.
    Brett O'Donnell, a senior adviser to Lindsey Graham, summed up Thursday's epic rant up as "political theater at its worst."
    "Yesterday he had the stage all to himself," O'Donnell said. "For 95 minutes. It was uninterrupted attack time for him."
    Of course, Trump's display in Iowa wasn't entirely unscripted. The state, home to the first-in-the-nation caucus on Feb. 1, is where Trump is facing his steepest competition from Carson.
    The bombastic ex-reality TV star appears most energized and colorful at his own campaign rallies, when he's fueled by the energy of thousands of supporters and can speak uninterrupted for as long as he wants. His unfiltered anger has no doubt been a major force behind his success so far. In a cycle where anti-establishment sentiment is running deep in both parties, Trump has regularly deployed deeply negative and impassioned rhetoric to tap into that very angst.
    Earlier this year, Trump slammed the Republican National Committee for being biased and repeatedly threatened a third-party run -- before deciding that the RNC was "fair," after all. Last month, his campaign apologized for retweeting a message that suggested Iowans had mental problems -- on Thursday, Trump went after the people of Iowa, asking whether they were "stupid" to believe Carson's story.
    And it's not just his political rivals that have been on the receiving end of Trump's volatile behavior -- it's the media, as well.
    Trump has more than once profusely praised a reporter, only to turn around and suddenly attack their journalistic integrity.
    He's had a long-running and on-and-off feud with Fox News, including with anchor Megyn Kelly. He's accused her of being "really off her game," retweeted a message that called Kelly a "bimbo," and drew furious backlash for saying Kelly had "blood coming out of her wherever" at a debate.
    After all that, Trump abruptly ended the attacks, saying Kelly was "very nice" to him on one of her shows.
    Following this week's GOP debate co-hosted by the Wall Street Journal, Trump praised the paper's Washington Bureau Chief for executing an "elegant" event. But the next day, he blasted out a series of tweets slamming the publication for a critical editorial that didn't sit well with him.
    "When and how are the dummies at the @WSJ going to apologize to me for their totally incorrect Editorial on me," Trump wrote.