*Positively Wrong*
A linguistics professor was lecturing his class.
"In English," he explained, "a double negative forms a positive. In some languages, such as Russian, a double negative is still a negative."
"However," the professor continued, "there is no language wherein a double positive can form a negative."
A voice from the back of the room piped up. "Yeah, right."
SOURCE: Pastor Tim http://www.cybersalt.org/cleanlaugh