As South Koreans took to the streets this month to demand the ouster of their president, some found an unexpected outlet to express their anger: jokes and satire.

They displayed banners and flags with wacky messages about cats, sea otters and food. They waved signs joking that President Yoon Suk Yeol’s declaration of a state of emergency had forced them to leave the comfort of their beds. Images of the flags spread on social networks.

The idea was to use humor to build solidarity against Mr. Yoon, who has vowed to fight his impeachment over his ill-fated Dec. 3 state of emergency decree. Some waved flags for non-existent groups such as the so-called Dumpling Association, parodies of real groups such as labor unions, churches or student clubs.

“I just wanted to show that we’re here as part of the people, even though we’re not really part of a civic group,” said Kim Sae-rim, 28, who was waving a dumpling group flag at a recent protest she went with friends. Some groups mentioned other local favorites like pizza and red bean bagels.

Kwon Oh-hyouck, a veteran protester, said it was the first time he had seen such flags appear during demonstrations in 2016 and 2017 which eventually resulted in the removal of President Park Geun-hye. Mr. Kwon said satire was part of the Korean spirit of protest.

“People satirize serious situations, even when those in power come out with guns and knives,” he said. “They are not intimidated.”

In the past month, protesters have brought out a wide range of unorthodox groups. Some were self-proclaimed home guards. Others gathered like people suffering from nausea.

Lee Kihoon, a professor of modern Korean history at Yonsei University in Seoul, said he believed the flags at this month’s protests were an expression of the diversity of people encouraged by the president’s attempt to impose military rule.

“They are trying to say, ‘Even for us who have nothing to do with political groups, this situation is unacceptable,'” he said. “I’m not a party member or anything, but this is outrageous.”

Some held signs mocking Mr. Yoon, saying he separated them from their pets at home and disrupted their routine of watching Korean dramas. One group called itself a union of latecomers, referring to the idea that the need to protest the emergency forced them to move their appointments.

And of course, there were animals, both real and fake.

South Koreans have shown that protests for serious causes – such as the overthrow of a president – can still have an inviting, upbeat and carnival atmosphere.

“I don’t know if the protesters realize it, but even though they’re angry, they haven’t become solemn, heavy-handed or moralistic,” Mr. Lee. “The flags had the effect of easing and relaxing the tension.”

On the day when the representatives voted for the impeachment of Mr. Yoona, protesters who were K-pop fans brought lanterns to the rallies and danced to pop songs blaring from the speakers. “Even though it’s a serious day,” said Lee Jung-min, a 31-year-old Big Bang fan, “we might as well enjoy it and keep our spirits up.”