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?"

An invisible man is here to see you
Nurse: Doctor, there is an invisible man in your waiting room.

Doctor: Tell him I can't see him now. Next.