Standing on your feet for hours during the freezing cold, not having a single sip of water because there’s no restroom to relieve yourself, and being crushed on all sides by strangers sounds hellish — but some 2 million people do it willingly every year.

So it goes in Times Square in the hours before the ball drops at midnight on Dec. 31. This year’s forecast calls for temperatures in the teens, as well as a ground cover of snow left over from days before. And Brian Alvarado, 18, plans to be right in the thick of it for the fifth year running.

The Westchester teen, a student at Columbia, aims to show up — wearing long johns under his clothes — with pals around 2 or 3 p.m. He says it’s all worth it to catch the likes of Maroon 5 and Mariah Carey gratis. “It’s a huge free concert!” he said. “If you get a good spot, you don’t notice the cold and how long you are waiting.”

Lynn Crisci begs to disagree.

When the Boston-based patient advocate, 40, attended the festivities two years ago, She recalled feeling “herded like cattle” inside the sectioned-off pens in the upper 40s, blocks from the ball-dropping action.

“It was absolutely freezing,” she added. “I couldn’t believe how many people brought babies and small children. We felt so badly for kids, we were lifting them over the barriers” — so they could go to the bathroom on the street.

Indeed, there are no port-a-potties, and local businesses turn away revelers in need, as Jeryl Lippe learned the hard way.

When the 22-year-old from Mahwah, NJ, hit Times Square with her boyfriend, Gabriel, four years ago, she smuggled in vodka in a water bottle. (Alcohol, along with large bags and umbrellas, is forbidden; plus, Lippe was underage.) She didn’t eat anything other than a breakfast bagel, and didn’t have her illicit drink until the end of the day. But, “by the time it was turning midnight, I had drunk a lot and was desperate to go to the bathroom,” said the junior social-media editor. “I tried to find someplace to go — hotels, restaurants,” she said, but she was denied.

Alvarado recalled how one of his friends gave up and urinated in the street, adding, “I’ve heard stories of people who wear [adult] diapers.”

Katelyn Wollet, a 24-year-old photographer, traveled from Michigan to NYC for New Year’s Eve three years ago — taking a 16-hour Greyhound ride with a guy with whom she’d only been on two previous dates. She and Jimmy Tomczak, an author, spent more than 13 hours in Times Square “getting to know each other,” she said. There was one hitch, however: “[Police officers] don’t let you sit down. If you do, they’ll say, ‘You need to get up.’ ”

On the upside: Wollet and Tomczak are still together.

And who knows, maybe Alvarado will meet someone special this year. “I talk to strangers” to pass the time, the teen said. “You meet people from places around the world. Sometimes you see people from Spain or South America eating grapes.” (A Latin American tradition dictates that revelers eat 12 grapes and make a wish at midnight.)

Crisci said she would consider returning to Times Square one New Year’s Eve — “but I would definitely get a hotel room that overlooks the square, instead.”

Additional reporting by Kirsten Fleming