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!"
"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, what are we doing these days?"
"I'm writing the second chapter of my thesis, on how rabbits devour wolves."
"Are you crazy? Where is 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 next to some bloody and furry 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.