According to this story in World Science, researchers analyzed monkey calls
and determined that some of them could only be described as "comments."

http://www.world-science.net/exclusives/040901_commentfrm.htm

These were supposedly the first documented monkey calls that appeared to
make reference to a third party not involved in the vocal exchange. The
monkeys seemed to be making an observation or a comment about what they were
seeing, the researchers found.