"Last year it was coming more and more," says Genese Perez, the creative director at Monarch Rooftop and Addison Hospitality Group in New York City. Perez notes the bar is a common spot for corporate happy hours and meetings, and she's seen the trend evolve. "Now it's come full swing and those high end (tequilas) are really taking over, and it's all Tequila Sodas."

It'd be a herculean task to find the ur-Tequila Soda drinking finance bro. It's like any other drinking trend: The true background is a mix of fact, fiction and hyperbole. What is clear is that the trend follows the general rise of Americans drinking more (and better) tequila than ever before. The "super premium" sector of the tequila market has grown more than 700 percent since 2002, and there are some 140 registered tequila companies. With more tequila being consumed, Americans are finding new ways to drink it besides shots and Margaritas.

"If you think deeper, it's the people [drinking Tequila Sodas] who don't like taking tequila shots and don't want to upset the person buying drinks," Sam Richardson says. Richardson is in his mid-20s, and used to work at Merrill Lynch before focusing full time on starting his vodka company, Vegas Baby. "Tequila Soda started because people didn't want to upset the crew."

As with any trend, it's not universal. People will drink what they like to drink. Before recently, however, "Tequila Soda" wasn't even in the lexicon of appropriate drink orders for corporate happy hours or weekend benders. Now it's been added to the short list along with sipping tequilas, Perez says. Bartenders have noticed it as well as people on the other side of the bar. A finance worker in his mid-20s texted me on his lunch break saying the drinks he sees people order most are obvious: Old Fashioneds (for stereotypical cocktail drinkers), Vodka Sodas ("because bros are trying to stay fit and are basically baesic (sic) bitches in suits") and Tequila Sodas.

"Continuing on my baesic (sic—ED. NOTE: Urban Dictionary says he is putting the "BAE" in basic) bitches in suits," he says, "[tequila is] an elevated 'more bro' booze to mix with your soda. And I think there are probably a lot of people who drink it. But it's not mainstream, so it'll appeal to people like 'Wow, that's what the bros are doing next? I gotta get on that.'"

While the Tequila Soda is not as ubiquitous in bars as the Old Fashioned yet, it's definitely not a new drink altogether. It is essentially just a stripped down version of the Paloma, which is one of the most popular drinks in Mexico and quickly growing in the U.S. Mixing soda with a spirit is one of the easiest things someone can do to make a liquor more accessible. Vodka Sodas (a drink that Richardson says older finance types still order more than anything else) are an easy example, as are Japanese Highballs, which are so ubiquitous in Japan that they're sold in vending machines. Quality tequila that's meant to be sipped, not shot, falls into a similar category as Japanese whisky. You still get the main flavor of the tequila, but the drink lasts longer and doesn't hit you as quickly.

In a completely serious Business Insider story from 2013 titled "The Definitive Guide To Drinking Like a Wall Streeter," the writer advises that "soda is your friend in general." Soda reduces the chance of a hangover the next day, and is meant for mixing with comparatively expensive spirits like Grey Goose or Johnnie Walker Black. Whatever you get, the piece emphasizes, know your brand and make sure that your brand is something that people recognize. It's tequila brands, and not just Patron, that are highly identifiable today.

"We are going through bottles and bottles of Don Julio like crazy," Perez says. "It's interesting because people are just now hearing about (different) tequilas and they're sticking to the brand names they know."

Five years ago, Perez says, Monarch had around five tequilas on the market. That number is now in the 20s with more expensive bottles from brands they already carried, like Don Julio 1942. The bar also began picking up relatively new brands, like Casamigos. Cheap mixto tequilas are out the door, and more expensive 100-percent agave versions are in. Casamigos in particular gets called out a lot, Richardson says, "just because [it's connected with] George Clooney and people want to say they know the backstory." Backstories, after all, are perfect fodder for happy hour small talk when you've spent countless hours in close proximity to someone, yet know nothing about them other than how they can organize a spreadsheet.

Another reason finance bros are gravitating to Tequila Sodas and tequila in general is the notion that it's a healthier drink. It's a low calorie drink compared to something like an Old Fashioned that has added sugar muddled into it. Sitting in an office all day isn't exactly ideal for staying fit, and soda is a low calorie mixer that finance bros have always taken advantage of. It was just mixed with whiskey and vodka in the past. On a thread about drink orders for happy hours on the chatroom Wall Street Oasis in 2013, user F. Ro Jo posted that he drinks "Makers and soda" because he's "gotta watch the waistline." Another user with the handle Unforseen posted, "Vodka Sodas flow here like water from the water cooler."

Then, of course, there's all the talk about tequila being an upper rather than a downer, which is a myth that never dies. "It's spread so much that I can say it and know it's a lie, but people will believe it," Richardson says. Perez attributes part of the prevalence of the myth to the fact that tequila is made with blue agave, and people believe that agave is a better sugar for your body than straight cane sugar.

All of these reasons—marketing, the health myths, more visible and celebrity backed brands—have led to a tequila demand that's outpaced supply recently. An agave shortage for tequila production is causing prices to rise, but that's not exactly a bad thing for a finance crowd that's known for indulging on affordable luxuries. Perez says that the demand from the finance crowd wouldn't decrease with a price bump, just like vodka demand didn't decrease in its prime as prices increased for the major brands. Tequila Soda popularity, she predicts, will sustain for a couple more years—or at least until the next trend comes along.