A new Clinton mystery has hit New York City and Washington, D.C. with the surprise display of posters declaring the Clintons as “America's Most Dangerous Family" and "America's Lannisters."

Pulled by advertising bikes over the weekend, the posters use themes from TV's " Game of Thrones" and " House of Cards" in portraying Bill, Hillary and Chelsea Clinton -- and advisor James Carville -- as evil, though they don't indicate exactly what the advertising is for.

One of the ad posters appears similar to the style of the hit Netflix series, "House of Cards." The poster is in black and white and shows Bill and Hillary under an upside down U.S. flag, the sign of distress. That poster reads, “America's Most Dangerous Family.”

The second offers a "Game of Thrones" reference with pictures of the Clintons and longtime aide Carville as "America's Lannisters." In the smash HBO hit, the powerful and rich Lannister clan is described by TV Guide as controlling and backstabbing. Chelsea is depicted as the female version of Joffrey Baratheon, the loathsome and entitled king in the series.

Both carry the date: "7.22.14."

The ads were pulled through downtown New York and, in Washington, stopped in front of the White House over the weekend.

One Twitter commentator speculated whether it might be a PR stunt funded by the Koch brothers. A Koch associate, however, denied any knowledge of the ads.

One tipster asked the cyclists what the posters were about, but they remained tight-lipped. The guerrilla marketing campaign could be to promote a new movie, television series or book about the Clintons, Secrets hears.

Paul Bedard, the Washington Examiner's "Washington Secrets" columnist, can be contacted at pbedard@washingtonexaminer.com.