Presumptive GOP nominee Donald Trump has shelled out $35,000 to something called "Draper Sterling" for "web advertising." But oddly enough, nobody seems to know what "Draper Sterling" is, although it does have a name that's very similar to the one used by the advertising agency in the hit show "Mad Men."

The payments to "Draper Sterling" were buried in Trump's FEC report for the month of May, which was released on Monday. The disclosure said the entity was headquartered in a suburban New Hampshire home owned by Jonathan Adkins, who also owns a political "data analytics" company called "Dynamic Solutions Systems."

Adkins is the co-founder of a medical device start-up alongside Paul Holzer, a former Navy SEAL who has worked in Massachusetts and Missouri for Republican candidates. Adkins and Holzer were also each payed $3,000 for "field consulting" by the Trump campaign in May, ThinkProgress notes, and Holzer listed his address as Adkins house, the same place where Draper Sterling is apparently headquartered.

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And from there, according to ThinkProgress, the situation just gets stranger.

Draper Sterling's one other apparent mention in public documents surfaces in a May complaint against "Patriots For America," a federal super PAC involved in Missouri's gubernatorial race. According to the complaint, Patriots for America has a $56,234 debt to a "mysterious" group called "Draper Sterling, LLC," which the economics professor who filed the complaint characterized as "highly unusual" and possibly illegal.

As it turns out, "Patriots For America" is run by Holzer's brother, Adam McClain. Its listed number instead goes to Grace's Grantham Cafe, which was supposed to be opened over Memorial Day, and is registered to Adkins. When ThinkProgess called the number, Adam McClain picked up, who refused to answer any questions about "Draper Sterling," the cafe, or Holzer.

So what did Adkins, Holzer, and "Draper Sterling" do for Trump? That's unclear, and the Trump campaign has not yet returned CBS News' request for comment.