Nancy Pelosi didn't look quite like herself as Donald Trump delivered a State of the Union address on Tuesday night that featured more boasts than policy proposals. She fidgeted. She contoured her face. She waved her finger. She shook her head in what clearly was disgust.

The California Democrat had been chatting with Vice President Mike Pence before the president arrived to address a joint session of Congress for a fourth time, this time as a candidate for re-election. Then, it happened. And everything about her changed.

Mr Trump, as is custom, handed the vice president and speaker copies of his speech. Ms Pelosi took her version and extended a hand to Mr Trump, as is custom. The norms-busting president, shot her a brief scowl and refused to shake her hand.

For the entirety of the lengthy address, Ms Pelosi clearly had something on her mind as her Democratic caucus jeered Mr Trump at every turn - when they were not sitting shocked and ashen-faced. Then, something else happened: Ms Pelosi tore the pages of her copy into pieces and tossed them on the dais in front of her before Mr Trump had even left the grand stage.

The shocking moment represented a low point in the duo's combative relationship - and there may be no bottom. Here are three takeaways from a truly bizarre State of the Union night in Washington.

'Manifesto of mistruths'

Slacked jaws across the capital city and country had not yet been restored to their usual positions when the barb-trading began.

Pelosi's office fired off a tweet defending her decision to defile Mr Trump's speech at a moment she knew the cameras would be trained on his big finish. She wrote this over a picture of Mr Trump declining to shake her hand: "Democrats will never stop extending the hand of friendship to get the job done #ForThePeople. We will work to find common ground where we can, but will stand our ground where we cannot."

The speaker also issued a blistering statement that focused on Mr Trump's SOTU claims about healthcare, taking umbrage with his vow to protect citizens with pre-existing conditions. Ms Pelosi panned what she called his "manifesto of mistruths," adding his speech "gave no comfort to the 130 million Americans with pre-existing conditions or the families struggling to afford the prescription drugs the need."

More than a bit out of character, Mr Trump had ignored her slight by late Wednesday morning. But the White House fired back, .

"America saw an incorrigible child ripping up the State of the Union," White House Counselor Kellyanne Conway told reporters, adding Ms Pelosi appeared to be "muttering" to herself throughout the speech, suggesting the speaker is "at the end of her tether."

Should Mr Trump win a second term and Ms Pelosi keep her gavel, their boiling bad blood seems an obstacle to deals even on issues they mostly agree, like lowering prescription drugs and overhauling the country's aging infrastructure.

Trump's turn

Perhaps no Democratic politician gets under Mr Trump's skin more than the speaker of the House.

She needles him at press conferences and in media interviews. She can be sizzlingly sardonic in taunting tweets directed at him. Aides acknowledge the president views her as perhaps his most worthy adversary.

But he flipped the script on Tuesday night.

When the president snubbed her extended hand - in her chamber - he got under her skin like he never had before.

She even flashed a bit of temper, saying tearing up his speech was the "courteous thing to do, considering the alternative." Yikes.

'No agenda'

Mr Trump made a few calls for Congress to send him legislation or work with his administration on an issue - but far less than other presidents have while standing in the ornate chamber.

To be sure, he was there to talk about what he's done for his conservative base to keep them energized to vote come November. From the top of the speech, he served up red meat for them.

"From the instant I took office, I moved rapidly to revive the US economy - slashing a record number of job-killing regulations, enacting historic and record-setting tax cuts, and fighting for fair and reciprocal trade agreements," he said. "Our agenda is relentlessly pro-worker, pro-family, pro-growth, and, most of all, pro-American."

"The people are the heart of our country, their dreams are the soul of our country, and their love is what powers and sustains our country. We must always remember that our job is to put America first," Mr Trump said.

As he uttered the last words, Ms Pelosi, seated over his left shoulder, looked bewildered.