Three … two … one! Happy New Year!

What happens next is, depending on the situation, a lovely moment with your partner, a Roman tradition, a purifying act, evidence of fond friendship, your best chance of making the magic happen, the worst decision ever, a masterpiece of avoidance, or one of those weird customs you put up with once a year.

We speak, of course, of the New Year’s kiss.

Granted, traditions differ. Some partyers wouldn’t dream of sharing kisses just because 2017 has begun, while others can’t imagine not greeting Jan. 1 with a quick peck on the lips.

Let’s break it down:

A lovely moment with your partner

You’re both feeling festive. What with midnight, the Champagne and the frisson of starting the year together — whether it’s your first or your 14th — sharing a romantic kiss is simply the best. English and German folklore says that the first person you encounter in a new year, and how you encounter them, sets the tone for the future. So a kiss renews a couple’s commitment to each other. Which is nice, when 365 days lie ahead.

A desperate superstition

English and German folklore invented a flip side to the tradition with this suggestion/threat: Not kissing someone at midnight would lead to a lonely and loveless year.

A Roman tradition

Who started all this midnight smooching? The ancient Romans, natch, who embraced the Festival of Saturnalia. This winter solstice thing got moved later over the years until it got tangled up with Christmas — which it definitely is not. How it reached Dec. 31 isn’t clear, as few things that happen after midnight ever are.

Saturnalia was about upending social norms. Masters served slaves. Restrictions on women were eased. People gambled openly. Drinking was involved. Inevitably, such bacchanalia led to people kissing each other. Eventually, of course, Rome burned.

A purifying force

During the Renaissance, masquerade balls were the rage. New Year’s Eve masks symbolized the evil spirits and vice of the past year. At the stroke of midnight, the masks were removed and kisses exchanged as a purifying force, presenting the new year as a clean slate.

And the cycle began again, for without a year’s worth of accumulated evil, how could anyone bestow those purifying kisses?

A masterpiece of strategic avoidance

There’s an art to avoiding a close encounter of the lip-lock kind — whether you’re a man or a woman fending off a woman or a man.

“The Complete Worst-Case Scenario Survival Handbook: Holidays” suggests extending your arm “in a wide arc and move into a hug position.” Or try the “head-and-shoulders maneuver,” a last-second rotation of your shoulders and head to present your cheek.

Of course, it should go without saying that no one should be kissed against their will. And yet it must be said.

The good news is that we now are talking more openly about sexual assault, which — hello! — includes unwanted kisses when you’ve indicated no interest, whether with an upheld hand, a shaken head or simply, “No.”

Hey, Victorian guidebooks once advised women to put pins in their mouths to avoid being kissed in the dark when trains went through tunnels.

An act of fond friendship

There are those wonderful parties where you feel blessed to have such friends. Maybe you’ve vacationed together, lent supporting shoulders through tough times, or laugh so hard you cry whenever you gather. A kiss among all at midnight, purse-lipped and chaste, is an honest, platonic expression of your bond. It’s wishing each other the best in the new year, with genuine love.

Your worst decision ever

Your crush is standing over by the pretzels. You can’t remember when you first fell for them, but the feeling hasn’t dimmed. So far, there’s the passing chitchat in the coffee shop, or when you walk into work at the same time. With everyone kissing each other at midnight, it could be the perfect moment to declare your heart’s desire. You approach as the confetti is falling — and their face fills with alarm.

Your best decision ever

Your crush is standing over by the pretzels. You can’t remember when you first fell for them, but the feeling hasn’t dimmed. You seem to click whenever you meet — at the office, or at a mutual friend’s cabin, or at the coffee shop where all your friends hang out. The attraction seems mutual. With everyone kissing each other at midnight, it could be the perfect moment to break the boundary of being pals and discover that flash of recognition in their eyes.

One of those weird customs you put up with once a year

Maybe this is why people start staying in on New Year’s Eve. As if the drunken drivers aren’t enough to worry about, as if the cheese balls you eat trying to stay awake won’t betray you, you’re just tired of the prospect of smooching — however briefly — with people you’d otherwise never dream of kissing.

Isn’t it enough to clink glasses? Or do you need to lighten up and accept that you’re overthinking this?

Three words: Trust your gut.

Pretty soon, it’ll be five minutes later, and people will be pulling on their coats and gloves and looking forward to a good night’s sleep.

Because 365 days lie ahead.