Their crime: engaging in a water fight.
The evidence: water guns and bottles.
The accusations against them: violating Islamic principles and norms.
It sounds absurd, but sadly it's the reality in the Islamic Republic of Iran where, among other things, having a bit of fun can also land one in prison.
The young women and men had gathered last week in a Tehran park, ironically named the Garden of Water and Fire, and splashed water at each other.
The event, planned and organized on Facebook, had reportedly attracted around 800 people. Pictures of the event show happy girls and boys soaked with water, carrying colorful water guns.
They weren't chanting opposition slogans or protesting against the government, but they were having a good time in public, which can be seen to challenge state-enforced codes of conduct. Their photos were shared on websites, blogs, and social media.
Many praised them for their creativity, for managing to organize the event, and also for having fun, which is not always easy in Iran.
Not everyone was happy, though. Conservative websites used the "incriminating" photos to accuse the young people of immorality and corruption.
On July 31, Tehran's police chief, Hossein Sajedinia, said a group of young Tehran residents were arrested for splashing water at each other. Sajedinia warned that the police would act against others who disrupted "public order and security." He provided no details on the number of arrests.
One parliament deputy, Mousa Ghazanfarabadi, said the organizers of the event were trying to distance the youth from Islamic principles and the values of the Islamic republic. Another lawmaker, Hossein Ebrahim, called on the judiciary to take action against similar events.
The water fight is one of the latest such events to take place in Tehran in recent months. Last week, in another park in the capital, a group of young men and women got together for a game of dress-up in unfashionable clothing.
In January, young people with curly hair celebrated their locks at a gathering in another park (see video from the event).
There were also gatherings for paintball, kite flying, and blowing bubbles. All the events are said to have been organized through Facebook.
It's not clear why the water fight has caused more sensitivity than the previous events.
One reason could be the photos of happy boys and girls mingling that were widely shared on websites and social media. The event apparently attracted more people than the previous gatherings, which could be also a reason why the authorities felt the need to take action.
Officials, of course, are also wary of any kind of gathering, especially among youth, for fear it could take on antiestablishment overtones -- even perhaps in the case of these apparently apolitical events.
It could also be that the water-loving youths have become victims of the political rivalries between the different factions of the Islamic establishment.
The hard-line, pro-government Rajanews website attacked Tehran Mayor Mohammad Baqer Qalibaf over the case and accused his team of having been behind it.
The Hamshahri website, which belongs to Tehran's municipality, reacted by accusing Rajanews of lying, and saying that the municipality did not organize the water fight.
Both sides appear to agree on one thing: by engaging in a water fight, the young people have acted against Islamic laws.
Some of the young people, however, disagree. "All we want is a bit of joy," one participant wrote on Facebook. "So that Islam is not endangered during water fights, women on this side , men on the other," someone posted sarcastically on another of the Facebook pages devoted to the water fight.
The fun-seeking young people don't appear to be intimidated by the warnings and reported arrests. Some write on Facebook that there will be more actions in future weeks.
"At the worst case we will run away if the police come," wrote a young man on the Facebook page of "Water Gun Wars in Tehran."
The incident highlights the gap between the establishment and the population, of which about 65 percent are younger than 35 years old. It also highlights the shrinking tolerance of the establishment and the braveness of young people who, despite all restrictions, manage to find ways to breathe a bit of fresh air and be happy.
"Laughing and joy is becoming a rare phenomenon because of all the problems people are facing in this country," a Tehran-based observer who did not want to be named told Persian Letters.
-- Golnaz Esfandiari