You might have seen this viral video—a little girl pounds her chest at a zoo exhibit, provoking a gorilla to charge the glass. Reddit user loopdeloops recently shared a gif of the video, posting it to the WTF community:

And Reddit user burnSMACKER shared this amusing screenshot of the parents’ reactions:

But why did the gorilla attack the glass in the first place? One Reddit user gave a possible explanation for the gorilla’s behavior.

But is it true? The gorilla in the video was a 20-year-old male western lowland gorilla. According to the Smithsonian National Zoological Park:

“An adult male [western lowland gorilla] protecting his group may attempt to intimidate his aggressor by standing on his legs and slapping its chest with cupped or flat hands while roaring and screaming. If this elaborate display is unsuccessful and the intruder persists, the male may rear his head back violently several times. He may also drop on all fours and charge toward the intruder. In general, when they charge they do not hit the intruder. Instead, they merely pass them by. This demonstration of aggression maintains order among separate troops and reduces the possibility of injury.”

But Dan Cassidy—the Henry Doorly zookeeper—thinks otherwise. He suggests that the gorilla’s aggression wasn’t directed towards the little girl. Science Alert reports:

“Although the gorilla may have been engaging with the public to receive a reaction, the gorilla was most likely exhibiting typical gorilla behavior and likely posturing toward another male gorilla.”

Whatever the reason, one reddit user gives some final advice: