A guy goes to the zoo one day.
While standing in front of the gorilla's cage, a gust of wind swept some dirt into his right eye.
When he rubbed it, the gorilla went crazy, grabbed him thru the cage and beat the shit outta the guy.
A couple months later after his coma, he goes back to the zoo to find out what happened.
The zookeeper explained that rubbing your right eye means "F**k you!" in gorilla language.

Pissed the guy goes home to find out how to get revenge... he watches tv and finds out that gorillas like to mimic humans and hatches a plan...
The next day he purchased two large knives, two party hats, two umbrellas, and a large sausage.
he goes to the zoo and over to the gorilla's cage, where he places a set of items in the gorilla cage.

Testing his theory, he put on a party hat....The gorilla looked at him, looked at the hat, and put it on.

Next, he picked up his umbrella and flipped it open and closed a couple times...... The gorilla picked up his umbrella and did the same....

Then the man picked up his knife, whipped the sausage out of his pants, and sliced it in half !!

The gorilla looked at the knife..... looked at his own crotch..... looked at the man.... and started to rub his eye.