A linguistics professor says during a lecture that, "In English, a double negative forms a positive. But in some languages, such as Russian, a double negative is still a negative. However, in no language in the world can a double positive form a negative." But then a voice from the back of the room piped up, "Yeah, right."
How does a mathematician lecture their child? "If I told you n times, I've told you n+1 times..."
After 5 hours sitting in the bar, a man was in no shape to drive, wisely left his car parked and walked home. As he was walking unsteadily along, he was stopped by a policeman. "What are you doing out here at 2 am?", said the officer. "I'm going to a lecture.", the man said. And who is going to give a lecture at this hour?", the cop asked. "My wife." said the man.