i went to twycross zoo yesterday and whilst standing watching the chimpanzees, this female came right up to the window, looked me right in the eye, then turned round, raised her bottom in the air and started pointing at and patting it and bouncing it up and down like a hottie in a hip hop video! slightly to my embarrasment but much to the amusement of everyone else in the vicinity. just wondering what she might have been saying to me? "kiss my a$$" has already occurred to me!
Female chimps do this to male chimps to invite the male to smell her scent glands, which will indicate to him that she is in season, and ready to mate.
Chimps are bright enough to know that certain behaviour - this being an example - will provoke a reaction from visitors.
Her ladyship was just a bit bored, and fancied winding you up a little - just be grateful she wasn't a male, their 'wind-up' behaviour is far harder to explain to the children!!!!