He tweaked his nose at the ape and the Ape got mad and threw ape-crap all over the man.
The man went to the zookeeper and complained.
The zookeeper asked him what he had done to piss off the Ape.
He told him all the things he did.
When he got to the part about ‘tweaking his nose’ at the Ape, the zookeeper said
“Well, no wonder! Tweaking your nose means F-YOU in Ape-talk!”
So, the next day the man goes back to the zoo to get even with the Ape.
He did all the same stuff at the Ape and the Ape copied him, but instead of tweaking his nose at the Ape,
the man produced a big butcher knife from his back pocket, unzipped his fly, pulled out a sausage he had put there, whacked the end of the sausage off, and offered the butcher knife through the cage for the Ape to do the same.
The Ape looked up at the man in horror, and without hesitation, vehemently tweaked his nose at the man.