Negative vibes!

A linguistics professor giving a lecture explains that in English, prescriptive grammar dictates that a double negative creates a positive. For instance "I ain't got no money" would translate as "I have money."
He then goes on to explain that in most languages, using two positives will create a more emphatic positive.
However, the proffessor concludes, in no language does a double positive create a negative. A student, in the back of the class, shouts "Yeah, right!"

Courtesy: Blue-eyed boy