BANGKOK (Reuters) - Thai protesters splashed paint, daubed graffiti and sprayed water on the police headquarters in Bangkok on Wednesday, a day after dozens were hurt by tear gas and water cannon in the worst violence in months of anti-government demonstrations.Youth-led protests since July have become the biggest challenge to the establishment in years with their demands for the ousting of Prime Minister Prayuth Chan-ocha, a new constitution and reforms to curb the monarchy’s powers. Tens of thousands joined Wednesday’s protest, which turned the outside of the Royal Thai Police headquarters into a multicoloured mess. Protesters placed dog food at the gate for police in an insult to what they called “slaves of tyranny”. Some sprayed anti-monarchy graffiti. Protesters said they were enraged by the police response to Tuesday’s demonstration at parliament and the rejection by lawmakers of a constitutional reform proposal that could have considered the role of King Maha Vajiralongkorn. “We came here solely because of our anger,” said one of the protest leaders, Panusaya “Rung” Sithijirawattanakul. Police barricaded themselves inside and did not intervene.