A classroom full of first year Veterinary students were participating in their first day of anatomy class. For the lecture, the professor begins by unveiling a dead cow under a white sheet laying on an operating table.
The professor tells the class "In Veterinary Medicine, there are two qualities you must possess as a doctor - the first of which is a strong stomach. You cannot, under any circumstance, be disgusted by anything involving an animal's body."
For example, the Professor pulls back the sheet and sticks his finger right up the dead cow's butt, pulls out his finger and sticks it in his mouth. The students just stand there, paralyzed at what they see. "Now, go ahead and do the same thing, each of you," the professor says.
Freaked out, the students take several minutes but eventually take turns sticking their fingers up into the anal cavity of the dead cow, and then sucking on them. Once everyone is finished, the Professor continues on with his lesson... "Now, the second important quality you must possess is a keen observation. You see, I stuck in my middle finger up the cow's butt, and I sucked on my index finger... Now, learn to pay attention."
The moral: Life's tough, but it's even tougher when you're stupid.