TEHRAN, Iran — In the middle of the Summer Olympics in Rio de Janeiro, Iranians thought a referee made a bad call against an Iranian wrestler that caused Iran to lose the chance of winning another medal. Soon afterward, the online hate began. It is unclear how or from where these attacks originated, but it appears that Iranian netizens know how to find the online pages of their enemies. In a very brief amount of time, the target’s page was bombarded with unpleasant comments.

Whenever something upsetting happens at a sporting event, Iranian netizens attack those who they believe are responsible for the unpleasant incident. Soon the person’s page crashes and becomes unavailable due to attacks from Iranian users. This trend has occurred repeatedly during the past few years. Ivan Zaytsev, the famous Italian volleyball player, became the target of these attacks, as did Polish volleyball players who had been unsportsmanlike during an Iran-Poland match. Referees also have been cyberattacked. The best example is probably the Serbian referee of the soccer match between Iran and Argentina in the 2014 World Cup who failed to call for a penalty in favor of Iran. There also was the Australian referee who gave a red card to an Iranian player during the Iran-Iraq match in the 2015 AFC Asian Cup. The case of the Australian referee caused collateral damage, as Iranian users mistakenly attacked the webpage of a Maryland resident who had the same name as the referee.

In fact, this trend is not limited to personal webpages. Last month, a controversial decision was made by the judges and jury members during the over-105 kilogram (231 pound) weightlifting competition at the Rio Olympics, disqualifying Behdad Salimi. Furious Iranian netizens went as far as hacking the website of the International Weightlifting Federation itself.

This behavior is not necessarily always negative, as the active presence of Iranians in cyberspace has occasionally had positive results. For example, Academy Award winner Leonardo DiCaprio shared an image on his Instagram account of the drying Lake Urmia situated in northwestern Iran and asked for more international attention to the threat to this environmental treasure. In response, Iranian users posted 50,000 comments thanking the actor for his post.