In this picture taken on Friday, July 29, Iranian youths celebrate with their water guns, during their water fights at the Water and Fire Park in northern Tehran, Iran. Iran is trying to put down a new wave of civil disobedience - flash mobs of young people who break into boisterous fights with water guns in public parks. A group of water fighters was arrested over the weekend, and a top judiciary official warned Monday that "counter-revolutionaries" were behind them. Throughout the summer, Iranian police have been cracking down. In the first incident, in July, hundreds of young men and women held a water fight in Tehran's popular Water and Fire Park, spraying each other with water guns and splattering bottles of water on one another. Police detained dozens of those involved.(AP Photo/Milad Beheshti)