Flip Out D.C. brings together members of the LGBT community and their allies for a competitive night of playing a classic college game. (Marina Cracchiolo/The Washington Post)

At first, mastering a drinking game didn’t sound so appealing to Sergio Rivera. But he felt this was the right time to try.

Rivera, a 24-year-old financial adviser, moved into the District a few months ago from the Virginia suburbs. He had broken up with his boyfriend of three years. In a new place, at a new point in his life, he decided to use a tool that an increasing number of the city’s young, gay newcomers are using to find their place in the District: joining an LGBT-oriented recreational league.

Rivera began spending Sundays on the top floor of the Cobalt nightclub in Dupont Circle, where more than 100 people gather each week for a competitive version of flip cup organized by Flip Out DC, one in an ever-expanding list of leagues catering to the city’s gay residents.

“I had seen all the T-shirts and knew that if I wanted to meet new people, I had to do a league like this,’’ Rivera said. “I’m usually a reserved and conservative person, so it was a chance for me to come out of my shell and be a part of the center of the gay community.”

The District has gained a reputation as one of the most gay-friendly cities in the nation, with a 2013 survey from Gallup estimating that 10 percent of residents identify as LGBT (lesbian, gay, bisexual or transgender). Another survey, by demographer Gary J. Gates, ranked the District eighth among 25 large cities in the number of same-sex couples per 1,000 households. The District was also the eighth jurisdiction in the country to recognize same-sex marriage.

FlipOut, the growing gay flip cup league that hopes to subvert stereotypes about the LGBT community, holds a tournament on Jan. 19 in Washington. (Bill O'Leary/The Washington Post)

The local pride parade and the annual high-heel drag races have become some of the most popular events in the District, which has been transformed by the growing numbers of millennials, whom studies consider the most tolerant generation toward gays.

Over the past five years, karaoke and social sports such as competitive kickball have captured the imagination of many young District residents eager for playtime. But the LGBT-oriented social sports occupy their own niche.

First, players say, they’ve added a more comfortable way for gays to coalesce in the city away from the too-formal settings of professionals mixers or the dating pressure at nightclubs. In a few short years, the leagues have emerged as a gateway to the city’s gay social scene, particularly for the legions of newcomers moving into the District each month.

They got their start in fall 2010 with kickball. Martin Espinoza and his friends had formed a majority-gay team that played in one of the region’s many recreational kickball leagues.

Players on other teams were generally accepting. But Espinoza said he and his players began to notice some tension when they’d hang out with the groups afterward at mostly straight bars.

“We just never felt 100 percent accepted,” Espinoza said. “The last straw came at the end of the season. We were at a bar, and two of our members were being affectionate with each other. There were some looks and some stares and some remarks said. When that happens, it ruins the experience for everyone.”

So he started Stonewall Kickball. Coincidentally, a gay flag- football league had formalized, as well. Each grew instantly. More than 100 players started in the football league; there are now nearly 300. Stonewall Kickball started with 90 players; there are now 650.

Then came the gay bocce league. And darts. And coming soon, dodgeball.

According to Espinoza, the kickball league alone has spawned hundreds of friendships and romantic relationships, and even some marriages.

“Half of the people playing, we know,’’ Espinoza said. “And then the other half, we don’t know. They are new to the city and just moved here, or in the worst case, they have gone through a breakup and haven’t been out socially in a while.”

On summer weekends, 17th Street NW in Dupont Circle is packed with men and women playing kickball. In the fall, men crowd Logan Circle to play on the gay bocce league’s teams.

This being winter, flip cup is where the action is.

For those who thought college was only for studying, flip cup is a popular party sport among students. Here’s how it works: Two teams — in this league, groups of six to eight — stand on opposite ends of a long table, holding large, plastic cups that contain a few ounces of beer. One person on each team chugs the beer, then quickly sets the cup on the table. Next, he must flip the newly empty cup upside down using only his fingers — not his palm.

When the player is successful, the next teammate chugs, then flips. The chain continues until all members of the team are finished. The first team to complete the circuit wins the round. At Flip Out DC, nine rounds make a match.

“More fun than it looks,” Rivera said. It’s also harder than it sounds.

Chris Chase founded Flip Out DC to complement the kickball off-season. During the second week of play this year, the scene inside Cobalt looked manic — tables lined with hunched players flipping away. Some did so with precision, some with abandon.

In between rounds, dancers huddled and wiggled to the new Beyoncé album. In one corner, a team of recent Georgetown grads celebrated winning their first flip cup game.

“We worked hard perfecting our skills for four years, and we’re not gonna lose them now!” one said to great applause.

In another, a team’s captain delivered a serious analysis of a recent loss.

“Unicorns, I got to be honest, that wasn’t our best game,” she said, using the name of her team. “We were a little ragtag out there. We gotta raise up our level of play.”

As the flip cup league has grown to about 130 players on 10 teams, Chase said he’s noticed some distinctions between them and other social-sport enthusiasts. For one thing, the kickball leaguers tend to be more athletic, although no more competitive.

While kickball tends to consist almost entirely of gay men, about one-third of the flip cup competitors are lesbians. Of the “six seasons” of Flip Out, four seasons have had predominantly lesbian teams place in the top three.

“It’s something that doesn’t happen very often where we have lesbians and gay men coming together in a social space, even though we’re fighting the same fight,” said Maegan Rees, 26, who works in education and plays on a team. “But since the league started, you find all sorts of people interacting together — a lot of professionals, a lot of students, gays, lesbians, straight people coming together to have fun.”

Rivera found himself on a recent Sunday in a purple T-shirt with a team known as Flippin’, Not Trippin’. Tables were set up on Cobalt’s dance floor, and the DJ was pumping tunes from Lady Gaga. Those walking around had to do so briskly — the floors were sticky from spilled Pabst Blue Ribbon, ricochet from the boozy war.

Rivera turned out to be a natural — he flipped the cups with ease. It took about 10 minutes for his team to win its match.

“Good job!” said his teammate Bex Young, hugging him. When Rivera looked around, he noticed a flier for a new indoor bocce league, complete with glow-in-the-dark bocce balls.

“Maybe I can join that, too,” he said. “I really need to make new friends.”