In a forest a fox bumps into a little rabbit, and says,

In a forest a fox bumps into a little rabbit, and says, "Hi,
Junior, what are you up to?"
"I'm writing a dissertation on how rabbits eat foxes," said the
rabbit.
"Come now, friend rabbit, you know that's impossible! No one
will publish such rubbish!"
"Well, follow me and I'll show you."
They both go into the rabbit's dwelling and after a while the
rabbit emerges with a satisfied expression on his face. Comes along a
wolf. "Hello, little buddy, what are we doing these days?"
"I'm writing the 2'nd chapter of my thesis, on how rabbits devour
wolves."
"Are you crazy? Where's your academic honesty?"
"Come with me and I'll show you."
As before, the rabbit comes out with a satisfied look on his face
and a diploma in his paw. Finally, the camera pans into the rabbit's cave
and, as everybody should have guessed by now, we see a mean-looking, huge
lion, sitting, picking his teeth and belching, next to some furry, bloody
remnants of the wolf and the fox.

The moral: It's not the contents of your thesis that are
important -- it's your PhD advisor that really counts.