BERLIN -- "Homeland" star Claire Danes walks through a narrow alley in Lebanon in the latest episode of Showtime's hit show, and passes a wall sprayed with graffiti in Arabic.

Producers had asked for something generic -- they suggested "Muhammad is the greatest" -- to give the feel of a Hezbollah-run refugee camp. But the group of three artists hired for the job decided to make a statement.

The message that was seen by more than a million viewers when the episode aired in the U.S. on Sunday was: "Homeland is racist."

The scene was actually filmed this summer in Berlin, but the group, calling itself "The Arabian Street Artists" -- the name itself a tongue-in-cheek jab at the initial solicitation from "Homeland" producers for the set work -- kept their actions quiet until the episode was shown.

On Wednesday, the three -- Berlin graffiti artist Stone, Heba Amin and Caram Kapp -- published the details on Cairo-based Amin's website, and the images quickly went viral.

"I think this really had an impact, and we obviously struck a chord," Stone, who goes by one name, told The Associated Press on Thursday.

"From the reactions we have seen, a lot of people had not so happy feelings about this show so there is a lot of happiness coming our way right now."

The caper was pulled off so well that even "Homeland" producer Alex Gansa gave the artists his grudging respect.

"We wish we'd caught these images before they made it to air," he said in a statement provided by Showtime. "However, as Homeland always strives to be subversive in its own right and a stimulus for conversation, we can't help but admire this act of artistic sabotage."

The Emmy award-winning show now in its fifth season is extremely popular, but has also been widely criticized for its depiction of Muslims, and also by the governments of Lebanon and Pakistan for its portrayals of their countries.

So when the show approached Stone this summer with the project looking for "Arabian street artists" who could add authentic-looking graffiti to the film set depicting a Syrian refugee camp, his first inclination was to say no.

"When we got the call we were really, really unsure if we would do anything for them and most of the artists I asked were totally saying no from the beginning, they had no interest in working for them," he said.

"And that was the conclusion that we came to ourselves -- until we got the idea we could insert our message into the show."

Stone said the artists initially considered using Arabic proverbs and slightly rewriting them with coded messages.

"The question was, how can we get a message across that is not so blatant that they will immediately recognize it," he said. "But then when the actual shooting started, it was pretty clear no one would even look at it."

So they started adding their blunt messages, including: "Homeland is a joke and it didn't make us laugh;" "Homeland is not a (TV) series"; "There is no Homeland"; "Black lives matter"; and "Homeland is watermelon" -- using an Arabic expression meaning something is superficial or a joke.

So far, Stone said, the artists have been overwhelmed by the positive reaction they've received -- mostly from the U.S. but also from the Middle East.

"We thought it had the potential to go viral, but when it really did yesterday that was a bit of a surprise," he said.

Mohamed Andeel, an Egyptian cartoonist who became popular among activists following the 2011 uprising against former President Hosni Mubarak, said the fact that no one from the series understood the words reflects the extent to which they respect Arab culture.

"I think it's a very smart move," said the 29-year-old satirist. "Artistically, it's smart and it uses graffiti very appropriately, corresponding to the idea behind graffiti in the first place."

- Sarah El Deeb in Beirut and David Bauder in New York contributed to this story.