A doctor is going round the ward with a nurse and they come to the first bed where the chap is laying half dead.
"Did you give this man two tablets every eight hours?" asks the doctor.
"Oh, no," replies the nurse, "I gave him eight tablets every two hours!"

At the next bed the next patient also appears half dead.
"Nurse, did you give this man one tablet every twelve hours?"
"Oops, I gave him twelve tablets every one hour," replies the nurse.

Unfortunately at the next bed the patient is well and truly deceased, not an ounce of life. "Nurse," asks the doctor, "did you prick his boil?"
"OH MY GOODNESS!" replies the nurse.