The "joke" is two-fold:

1) Beto O'Rourke was arrested for drunk driving in 1998. The photo used in the tweet above is O'Rourke's mugshot from that arrest.

2) While O'Rourke goes by "Beto" and many people think he is Hispanic, his full name is Robert Francis O'Rourke and he is Irish (and Welsh).

Get it? See, so the RNC takes a shot at Beto's past arrest AND the fact that he isn't actually Hispanic. Oh man, that is rich!

And by "rich," I mean classless, not to mention dumb. And unfortunately, those two words have come to define at least some of our politics — most notably among those who remain diehard supporters of President Donald Trump.

Here's what I mean.

One of Trump's most basic appeals in the 2016 campaign — and in the White House — is his rejection of the cult of political correctness. Time and again as a candidate, Trump insisted that the PC police had grown out of control, that regular people were no longer able to say what they thought for fear of being shamed by liberal elites — whether in the Democratic Party, the media, higher education or politics.

"I think the big problem this country has is being politically correct," Trump said in a Republican primary debate in 2016 . "I've been challenged by so many people and I don't, frankly, have time for total political correctness. And to be honest with you, this country doesn't have time, either."

People really responded to that idea. Many of them felt lost in the rapidly changing culture and hated that they were being told they had to change their long-held beliefs or risk being condemned by some elitists living in New York, Washington or Los Angeles. Trump's willingness to bully his Republican opponents with taunts about their size or their brain power, his deeply unconventional Twitter feed and even his occasional curse at a campaign rally all played to the growing sense that he wasn't like other politicians, that he told it like it was. And people liked it. A lot.

Then, somewhere along the way -- and I can't trace exactly when this happened so maybe it was always there -- Trump's anti-PC campaign morphed into something uglier, something more insidious and damaging to our politics.

What happened is that all behavior -- no matter how clearly inappropriate and rightly condemned -- began to be seen through the lens of Trump's war on political correctness.

When Trump was found to have said a series of deeply misogynistic things during an "Access Hollywood" taping, his supporters insisted that the freakout over his remarks was simply a function of elitists pushing their PC ideals down everyone's throat rather than simply just acknowledging that no one should talk like that about women.

When Trump said -- against all available evidence -- that the white supremacist violence in Charlottesville, Virginia, was the result of bad people on "both sides," his supporters said the uproar was because liberal elites hated him, rather than simply admitting that he was flat-out wrong in his contention.

When Trump has misled and lied -- more than 9,000 times , according to the Washington Post's Fact Checker, his allies have said that the media elites are wrong and that the president is the only one telling the truth rather than just saying that Trump doesn't tell the truth and that is a bad thing for the country.

This St. Patrick's Day tweet by the RNC is more of the same. Rather than say that it's tasteless and traffics in ugly stereotype -- all Irish people love to get drunk! -- the riders of the Trump train instead suggest that anyone offended by it either a) doesn't get the joke b) can't take a joke or c) both.

The elites love to make fun of other people but when their precious Beto is attacked look what happens! What a bunch of hypocrites! And they don't even know how to laugh at themselves!

The problem with that logic is this: The issues caused by our outrage culture -- and fueled by a Twitter-sphere forever searching for things to be offended by -- are real. But, the other extreme is even worse -- justifying whatever Trump says or does as simply the latest battle in his unending war against political correctness. In that world, anything is cool as long as it bugs the elites.

There are things that should be off limits -- in politics and life. Things that we can mutually agree are contemptible, whether we support the current administration or not. If everything can be lumped under the umbrella of "owning the liberal PC squares" than the ideas of tolerance, respect for differing views and a recognition of our common humanity all go out the window.

And that's not a world any of us should want to live in.