Protesters recently sang it from the public gallery when the prime minister was addressing Parliament, forcing him to stop and wait for them to finish. A half-dozen other members of the Cabinet have also had to listen to it at public engagements.
Government officials have acted bemused, but their discomfort is evident.
The same protest group has also inspired a resurgence of irreverent political graffiti along Lisbon streets, where huge colorful murals have appeared. Last weekend, dozens of people — ranging from children to pensioners — joined in the painting of a 13-meter (42-feet) by 13-meter mural calling people to Saturday's protests.
"It was really moving," said 41-year-old filmmaker Alexandre Azinheira, who designed the mural. With his retired parents unable to meet mortgage payments on their home due to pension cuts, he said he was spurred to act because the government had "betrayed" the Portuguese.
Another group, the White Revolution Movement, came up with the idea of putting officials' names on store receipts after the government threatened to punish anyone who didn't ask for a receipt for financial transactions. It was part of a crackdown on tax evasion by businesses.
The prime minister's personal tax number went around by email and cellphone text message and can now be seen on photographs of receipts posted on the group's Facebook page. Media reports claim receipts worth millions of euros now feature the tax number of government ministers — even though providing a fake receipt name carries a risk of up to three years in prison.
The Finance Ministry did not reply to a request for comment.
"We never thought it'd take off like this," the movement's leader Paulo Romeira said. "People leapt on board to show their disgust with the political class that has led us to where we stand today."
Passos Coelho, the prime minister, insists the protesters are an unrepresentative minority. "We shouldn't mistake a tree for a forest," he told reporters last week.
The response on Facebook didn't take long: a poster advertising Saturday's marches announced, "We are the forest."
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