First-year students at the UC Davis Vet school were receiving
their first anatomy class, with a real dead cow.

They all gathered around the surgery table with the body covered
with a white sheet. The professor started the class by telling them,
'In Veterinary Medicine it is necessary to have two important
qualities as a doctor: The first is that you not be disgusted by
anything involving the animal body' For an example, the Professor
pulled back the sheet, stuck his finger in the butt of the dead cow,
withdrew it and stuck his finger in his mouth.

'Go ahead and do the same thing,' he told his students. The students
freaked out, hesitated for several minutes, but eventually took
turns sticking a finger in the anal opening of the dead cow and
sucking on it.

When everyone finished, the Professor looked at them and said, 'The
second most important quality is observation. I stuck in my middle
finger and sucked on my index finger.' 'Now learn to pay attention.
Life's tough, it's even tougher if you're stupid.'