On May 28, 2016, Nathan’s Famous — the iconic hot dog vendor — celebrated their 100th anniversary by getting back to their roots: really cheap hot dogs. For a three-hour window that day, customers could get themselves a frankfurter for a nickel, a great deal in either century.

But in the early 1900s, it was too good to be true.

Nathan’s Famous got its start on Coney Island in Brooklyn, New York, when an immigrant named Nathan Handwerker found work at a restaurant named Feltman’s German Gardens. After he and his wife Ida amassed a savings of $300 — about $7,000 in today’s world, accounting for inflation — they went into business for themselves. Using his wife’s recipe and their life savings, Nathan opened a hot dog stand near the beach in 1916. His immediate strategy: compete on price. Feltman’s sold hot dogs for 10¢; Handwerker undercut his old employer and sold his for half that, at 5¢.

It didn’t work — at least not right away. Hot dogs are tubes of, well, who knows what — there could be anything inside that casing. Consumer protection laws in the United States were still new — the Pure Food and Drug Act, which established the Food and Drug Administration, was just signed into law just ten years prior. Coney Island’s regulars were understandably worried about the super-cheap hot dogs, and many stayed away from Nathan’s as a result. Sales were slower than expected, and it didn’t look like the hot dog stand would last.

Handwerker had a plan, though: all he had to do was somehow signal to passersby that his cheaper-than-expected hot dogs were safe for human consumption. The solution: fake doctors. The New York Times (via Smithsonian) explained the angle:

Mr. Handwerker hired white-jacketed young men to stand in front of his stand munching hot dogs. This brought in the “class” visitors. They had decided that Nathan’s franks “must really be good because all the doctors are eating them.”

This new customer base stuck — and so did the discount prices, at least for a generation. Nathan’s Famous sold hot dogs for 5¢ until 1944, when the business raised the prices to 7¢ to account for higher costs. But those days are long gone. Today, Nathan’s sells hot dogs at its original Coney Island location for about $4 and change.