A gorilla at the Dallas Zoo recently got some revenge on a group of nasty kids who were taunting him and calling him ugly.

With an annoyed facial expression so close to that of a human who’s been bullied too many times, the gorilla patiently waited for the right moment and then jumped against the glass, scaring the kids and making them scream before turning around to show them his backside.

Video of the incident has gone viral, with many viewers upset that the kids were allowed to taunt the animal that way, even if they were divided by a glass barrier.

“Where were the kids? All I saw was a gorilla on one side and monkeys on the other,” wrote one YouTube commenter.

Check out the video below and see for yourself.