This Weird English Language

Over the Thanksgiving weekend, I was reading some posts from one of my old websites and found this from 2007:

A lecture about English:

A linguistics professor was lecturing to his English class one day.
“In English,” he said, “A double negative forms a positive. In some languages, though, such as Russian, a double negative is still a negative. However, there is no language wherein a double positive can form a negative.”

A voice from the back of the room piped up, “Yeah, right.”