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."

A site foreman had ten very lazy men working for him...
A site foreman had ten very lazy men working for him, so one day he decided to trick them into doing some work for a change."I've got a really easy job today for the laziest one among you," he announced. "Will the laziest man please put his hand up."Nine hands went up."Why didn't you put your hand up?" he asked the tenth man."Too much trouble," came the reply.