In unison, anti-government protesters Wednesday called the King of Thailand a giant monitor lizard, one of the worst things that can be said of anyone in Thai, and spray-painted bus stops and pavement in the capital’s central business district with graffiti describing his sexual activity.

The insults demonstrated the increased daring of protesters in a country where criticism of King Maha Vajiralongkorn, 68, can be a criminal offense, and the security apparatus has a history of crushing dissent. They have been gathering by the thousands across Thailand for months now, calling for the military-linked prime minister to resign and for the constitutional monarchy to actually come under the constitution.

As demonstrators pushed their way to the gates of Thailand’s parliament on Tuesday, one of their leaders, Arnon Nampa, stood on a truck that doubled as a stage and threw down a bold ultimatum to the nation’s governing elite.