Orangutans tell predators to "kiss off"

From Yahoo News Weird Science:

"Researchers say they've observed the orangutans of Borneo make a crude "musical" instrument used to ward off predators. LiveScience reports that Borneo orangutans emit a "kiss squeak" call when threatened. They either use their lips to make the noise or strip leaves off a twig to use "in a bundle in front of the orangutan's mouth while the animal makes the kiss squeak." (Remember trying to use a blade of grass to whistle as a kid?)"

There's more info and a video at Discovery.com.