Gorilla

John was at the zoo and stop by at the gorilla enclosure. He decided to catch the gorilla's attention and started waving at it.

Upon seeing this, the gorillas became mad and threw rocks at him.

John was frustrated and asked the zookeeper what is going on?

The zookeeper explained that to the gorillas, waving means saying they are stupid and told John to beat his fists against his chest and shouting out loud as a form of greeting.

John did as what the zookeeper said and beat his fists against his chest and shouted out loudly in front of the gorillas.

John stopped and wanted to see the gorillas' reaction. The gorillas all started waving at him.