A professor is giving the first-year medical students their first lecture on autopsies and decides to give them a few basics before starting.
“You must be capable of two things for a successful autopsy. The most important factor is that you must have no fear.”
At this point, the lecturer sticks his finger in to the dead man’s arsehole and then licks it.
He then asks all the students to do the same thing with the corpses in front of them.
After a few seconds of uncomfortable silence, they all reluctantly follow suit.
Two students throw up, a third faints to the floor.
“The second thing”, continues the lecturer, “is that you must have an acute sense of observation. For example, you may or may not have noticed that just now I stuck my middle finger into the corpse’s anus, but I licked my index finger.”