Nerdy? Funny? Double positive!

Only a linguistics fan, an editor, or a hopeless nerd could enjoy this joke, which I ran across today via a leisurely Wikipedia-browsing marathon that eventually led me to the entry on philosophy professor Sidney Morgenbesser of Columbia University, who passed away at the beginning of this month. Fortunately, I am all three of these things.

A linguistics professor was lecturing to his 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."