This Sept. 19, 2007, file photo, shows the National Security Agency building at Fort Meade, Md.  (AP Photo/Charles Dharapak, File)

John Reusing will tell you that selling sausages and pierogi at the National Security Agency’s farmers market is no different than vending at other markets: Customers order, customers pay, he makes dirty sausage jokes.

Though there was that incident on his first day. After passing through the NSA’s security gates in his car, he pulled up a map on his cellphone to figure out where to drive. “Lots of security guards with guns yelled at me,” says the owner of Baltimore-based Ostrowski’s Famous Polish Sausage. “They did not appreciate having a camera phone pointed at them.”

The NSA farmers market, dreamed up by community-minded employees of the agency, began last year as an alternative to the cafeteria. The market, which launched with a handful of local food producers, was held every Friday in the spring and ran through November. It proved so successful that organizers brought it back this year — this time closer to the main building (a towering black cube on Fort Meade, Md., known simply as “OPS 2A”) and with almost double the number of food stands, which rotate weekly.

“Walk outside and bang, it’s right there,” says Dan Thomas, NSA’s chief of logistics for installations and logistics directorate, who estimates that more than 1,000 of the NSA’s 10,000-plus on-site employees visit the market every Friday.

Caitlin Icart, a veteran of the U.S. Marine Corps and a former employee of the NSA, frequented the market before she left the agency in September to pursue something more creative. Today, she and her husband roast organic beans through their company, Epic Bean Coffee, and Icart serves them at the market to former colleagues.

“A lot of friends come by,” Icart says. “They’re very supportive. I’m like, ‘OK, well have fun not seeing sunlight!’ ” as they return to their desks.

Becoming a vendor at the NSA farmers market is not quite as simple as filling out an application. Most participants are selected based on recommendations by employees and receive an email out of the blue asking them to apply.

“My original reaction was, ‘I don’t know about this,’” says Evan Siple, owner of Mobtown Meat Snacks, who was contacted by the NSA last year about selling jerky. “The NSA has ‘security’ in its name, and I’m like, OK, what am I going to have to do to get in?”

The process, according to vendors, is relatively painless: The initial screening requires them to share their birthplace, birthday, Social Security number and vehicle details. Once cleared, vendors pass through two security checkpoints on the day of the market, which takes about 30 minutes. Security K-9s smell coolers for anything suspicious, and are trained well enough that they don’t gobble slices of pizza or gyros.

Tucked behind the gates and closed to the public, the NSA farmers market has a captive audience ­­­— which leads to steady revenue, vendors say. “It’s kind of like fish in a barrel because the employees can’t really go out to lunch, and there’s no food delivery coming in,” says Ostrowski’s Reusing.

Of the vendors, Flavor Cupcakery and Bake Shop is particularly popular, consistently selling out its 750-cupcake allotments. On a recent Friday, as soon as the food truck opened its door, a line was stacked with men and women in civilian clothing and in camo, some of whom were holding bundles of sunflowers from the produce supplier.

The farmers market also gives NSA employees a chance to mingle across departments. It gives you the opportunity to bump into someone else,” Thomas says. “It’s an opportunity to interact with someone and say, ‘What’s going on with your day? I really like this pizza, or I really like these pickles.’ ”

Vendors, too, have struck up friendships with their customers — though they have to be cautious about how they interact beyond the confines of the market.

“We see them outside and it’s always a big secret,” says Ashwini Paraquad, the owner of Sexy Vegie, which sells vegan and vegetarian food. “It’s like, ‘Great seeing you on Friday!,’ but we don’t mention where we’ve seen each other on Friday.”

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