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."

An ounce of brains
A lawyer finds out he has an inoperable brain tumor.

It's so large, they have to do a brain transplant.

His doctor gives him a choice of available brains.

There's a jar of rocket scientist brains for $10 an ounce.

A jar of regular scientist brains for $15 an ounce.

And a jar of lawyer brains for the sum of $800 an ounce.

The outraged lawyer says, "This is a rip off! How come the lawyer brains are so damned expensive?"

The doctor replies, "Do you know how many lawyers it takes to get an ounce of brains?"