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."

Legal Troubles
"How can I ever thank you?" gushed a woman to Clarence Darrow, after he had solved her legal troubles.

"My dear woman," Darrow replied, "ever since the Phoenicians invented money there has been only one answer to that question."