A visitor to the Singapore Zoo snapped this photo of a chimp showing its middle finger. Chimps are highly intelligent creatures so I reckon this one could have learned it from the visitors or maybe even the zookeepers. Talking about zookeepers, the Singapore Zoo has an opening for an animal keeper. Part of the job is to prepare food and feed the animals, clean the animals and their exhibits and dens, and maybe teach the chimps some proper manners.
(Thanks Mr Big)