"In English," she 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 skeptical voice from the back of the room muttered "Yeah . . .right."
Very clever, and very subtle - it made me smile. I decided to look up the history of the story and found a bit more about it. As often happens, the story had been very slightly 'improved' in the telling but it led me to some other gems from the same source.
It seems that Oxford linguistic philosopher J L Austin made the claim that although a double negative in English implies a positive meaning, a double positive doesn't imply a negative. It was Sidney Morgenbesser who responded in a dismissive tone, "Yeah, yeah" (amusingly transformed into "Yeah, right").
It turns out that Morgenbesser had quite a reputation for wit.
Interrogated by a student whether he agreed with Chairman Mao’s view that a statement can be both true and false at the same time, Morgenbesser replied “Well, I do and I don’t."
When asked his opinion of pragmatism, Morgenbesser replied "It's all very well in theory but it doesn't work in practice."
In response to Heidegger's ontological query "Why is there something rather than nothing?" Morgenbesser answered "If there were nothing you'd still be complaining!"
A few weeks before his death, he asked another Columbia philosopher, David Albert, about God. "Why is God making me suffer so much?" he asked. "Just because I don't believe in him?"
Asked to prove a questioner's existence, Morgenbesser shot back, "Who's asking?"
A student once interrupted him and said, "I just don't understand." "Why should you have the advantage over me?" he responded.