as an example, the professor pulled back the sheet, stuck his finger in the butt of the dead cow, withdrew it and stuck it in his mouth. "go ahead and do the same thing," he told his students. the students freaked out, hesitated for several minutes. but eventually they 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."
thanks to cycledon for sending this to me.