I hate to be a party pooper, but there's a longstanding joke going around in philosophy that rests on a confusion. I take the following version from Wikiquote (s.v. "Sidney Morgenbesser"):

During a lecture the Oxford linguistic philosopher J. L. Austin made the claim that although a double negative in English implies a positive meaning, there is no language in which a double positive implies a negative. To which Morgenbesser responded in a dismissive tone, "Yeah, yeah."

How is "Yeah, yeah" a negative? Whenever I've heard the expression "Yeah, yeah," it wasn't meant to deny anything but to express frustration, as in "You're boring me; I've heard this all before; get to the point." Am I missing something? Unless I am, then philosophers should retire this joke, for it makes them look stupid.