Lemme see if I remember it correctly....
On the first day of the sem in med school, the professor and ten medical students gather around a corpse for their very first chance to handle one.
"Since it's the first day of the semester," the professor said, "i will only teach you two things that you muust learn if you want to pass my class. The first will be STOICISM. which means indifference to pain or pleasure. one must not feel loathing, fear or disgust upon seeing or handling internal organs or body parts. one must go beyond these feelings and view them with cold objectivity". to prove his point, the professor reached for the dead man's and stuck a finger in the butthole. he then pulled it out and placed it in his mouth and made sucking sounds. " now your turn" he told the students.
Stifling a smirk, the surgeon wanna-be's took turns in plugging the butthole with their fingers and with extreme courage, placed their fingers in their mouths, trying hard to ignore whatever horrid taste there might be.
after such tense moment, the professor then resumed his lecture. "i can see that you have proven yourselves rather well. now we come to the second point that i would like you to know. its about OBSERVATION. as i see it, you did not notice that i stuck my pointer finger in the corpse's butt and sucked on my middle finger. next time, pay attention. class dismissed. good day".