What on earth was that? For 90 minutes, we watched one candidate for president display the seriousness the office demands while the other did what was once unthinkable: show up unprepared for a globally televised job interview. The first presidential debate between reality-television star and wealthy builder Donald Trump and former Secretary of State Hillary Clinton was mind-blowing. Trump brought the vaudeville shtick that worked for him in the primaries to the main stage and bombed.

Trump’s performance was the rhetorical equivalent of hurling garbage on the lawn. A question about x would lead to mentions of y, z and whatever else came to mind. For instance, a response about Hillary Clinton’s emails led to a mention about the sorry state of New York’s LaGuardia Airport. And then there were the gasp-worthy moments that would sink any other presidential aspirant.

Clinton said the only time Trump’s tax returns were seen was when he sought a casino license. “[T]hey showed he didn’t pay any federal income tax,” the Democratic nominee charged. Trump’s response? “That makes me smart.” Neither average Americans nor the Clintons (who have released more than three decades of tax returns) could get away with that.

Hillary Clinton suggested a few reasons why Donald Trump is not releasing his tax returns during the first presidential debate, suggesting "maybe he’s not as rich as he says he is" and that he doesn't pay federal income taxes. "That makes me smart," Trump interjected. (The Washington Post)

Clinton hammered Trump on rooting for the 2008 housing crisis. Quoting the Republican nominee, she said, “He said, back in 2006, ‘Gee, I hope it does collapse, because then I can go in and buy some and make some money.” Trump’s response? “That’s called business, by the way.” Never mind the millions of devastated families who lost their homes and their jobs because of that collapse.

And for a candidate who says he is serious about earning the African American vote, Trump delivered a tone-deaf response to a question about healing the racial divide. “Secretary Clinton doesn’t want to use a couple of words, and that’s law and order,” said Trump. “We have a situation where we have our inner cities, African Americans, Hispanics are living in hell because it’s so dangerous. You walk down the street, you get shot.”

Not only did Trump continue to dabble in racial stereotypes about people of color, but he also used his answer to advocate the reinstatement of the unconstitutional practice of stop-and-frisk. A practice deeply unpopular with African Americans. And that was before Trump vigorously defended the racist birther lie he rode to the political prominence he used to win the nomination. An offensive delegitimizing of the nation’s first black president that remains an insult to millions of Americans, especially African Americans.

If there was one undeniable truth spoken by Clinton at the debate, it came in response to Trump’s dig at her for “stay[ing] home” last week. “I think Donald just criticized me for preparing for this debate. And, yes, I did,” Clinton said. “And you know what else I prepared for? I prepared to be president.” Kaboom.

Follow Jonathan on Twitter: @Capehartj