OK, concerned citizens, it’s debate time. Come back here and sit down! This is important. Let’s see if you’re prepared.

First, name the 10 Democratic presidential candidates who will be sharing the stage Thursday night. Give yourself a big pat on the back if you got them all. Light tap on the shoulder if you got six or seven.

If you failed to remember Joe Biden, Elizabeth Warren and Bernie Sanders, just leave the room. Admit it. You’re not going to watch this thing at all, are you?

Those of you who have demonstrated your commitment should now recall the debate goes on for three hours.

But there’s lots to look forward to! Will Beto O’Rourke obey the Democratic National Committee ban on “foul language”? He’s been using it a lot, particularly since the mass shooting in El Paso, Texas, when he laced into Donald Trump: “He’s been calling Mexican immigrants rapists and criminals. I don’t know, like, members of the press, what the (expletive)?”

Now this was totally understandable, given the terrible tragedy and Trump’s appalling history of racism. However, it’s one thing to blurt out a four-letter word at a moment of great stress. It’s another to have your campaign sell T-shirts that say repeatedly “THIS IS F*CKED UP.”

And what about Joe Biden? Everybody’s waiting to see if Biden will do something … strange. Maybe refer to one of the questioners as “Mom.” Or start telling stories about his adventures in a M*A*S*H unit in the Korean War, forgetting that was a TV series.

So, we’ll be watching to see if Biden bloops or Beto bleeps. Two deeply different matters, since so far in this campaign, swearing is pretty much the only area where O’Rourke is leading the pack. And nobody really cares that Biden accidentally called the president “Donald Hump.” Admit it — you chortled.

At the debate, our former vice president will be squished in between Bernie Sanders and Elizabeth Warren. That in itself should make it worth tuning in. If things go well, Biden could market T-shirts bragging “It’s Cool To Be In The Middle.”

There’s a popular presumption that Biden needs to perform at least decently in these events if he wants to win the nomination. But having trouble handling Warren in verbal combat is way different from being able to hold your own against Donald Trump. Particularly when the subject gets to whether a president should make up his own weather maps.

How much of the audience will be thinking about age? Biden, as the whole world knows, will soon turn 77. And Sanders is 78. Warren is 70, but she campaigns like a maniac — her record for posing for selfies with her fans has probably passed 45,000 by now.

Biden is taking things fairly easy, in a world where hitting 13 events in three weeks is sort of like goofing off. Still, if he can stand up on the stage for three hours trying to look both genial and hard-charging, that’s a pretty good sign that his age doesn’t matter.

Or at least doesn’t matter above all else. There are a few troubling precedents. One of the presidents who was oldest at the time of his inauguration, William Henry Harrison, died after a month in office. And the very oldest, Donald Trump, has been known to forget which country his father was born in.

Meanwhile, I’m betting Kamala Harris, 54, will try to vie with Pete Buttigieg, 37, in an appeal to the youth vote. Only saying that because she just sent out an anti-Trump fundraising email with the subject line “This dude’s gotta go.”

It’s sometimes a little hard to keep track of the actual issues when everybody’s vying to be youthful/likable/powerful/memorable/not-disaster-prone. Warren and Biden’s history of fighting over financial law will surely surface. They tangled in 2005 when credit companies wanted to make it harder for average Americans to declare bankruptcy. She sided with average Americans and he sided with, um, the banks. Which of them do you think will try to bring that up?

Happy to report there will no longer be any questions in which everybody has to raise a hand. (“Do you think a mass murderer who once assaulted a beloved guard who was the sole support of 14 grandchildren should be allowed to vote? Yes or no?”)

This is, of course, only one step in the long road toward … next year. Another debate is coming in October, which will probably have even more people. Remember the other candidates? How many can you name? Five? Fantastic. Eight? You’re beginning to get me a little worried.

One of them, Tom Steyer, has already qualified for the next round. He’s the billionaire who keeps running ads saying that he’s a better businessman than Donald Trump.

What do you think about that?

A) My cousin Fred who runs a pickle stand is a better businessman than Donald Trump.

B) Is Steyer’s slogan going to be “What this country needs is a hedge fund manager in the White House”?

C) Just promise me I won’t ever have to listen to Bill de Blasio.

Have a great debate night. Probably a good idea to skip the drinking games. There have been some suggestions you should take a shot every time somebody says “existential threat,” but remember, we’re talking about three hours here.

Gail Collins | The New York Times (CREDIT: Earl Wilson/The New York Times)

Gail Collins is a former editorial page editor and current Op-Ed columnist for The New York Times.