In a crafty sting operation, the UK’s Advertising Standards Authority (ASA) has found five online gambling firms in violation of the country’s rules for targeting ads at children.

The Guardian reports the authority went about their investigation by creating child “avatars,” or in other terms, they browsed the web in a manner similar to an underage person would. They then tallied the gambling ads they would see, and tallied the results.

Over two weeks, they saw ads from 43 online operators on public sites. Maybe most glaringly, 20 YouTube channels and two dozen children’s websites had gambling ads on them.

The ASA isolated five brands for breaking the UK’s advertising laws. They were: Vikings Video Slot, Redbet, Multilotto, Unibet and PlayOjo. None of those companies were advertising on YouTube, but they were advertising on sites frequented by children. Some 11 sites were found to have 23 unique ads, which appeared over 100 times in total. The biggest violator was Vikings Video Slot, which accounted for nearly half the unique ads, and the majority of the total appearances, according to ASA.