My family physician told me of an incident that actually happened to him back in the early days of his practice.
He said a woman brought her baby to see him, and he determined right away that the baby had an earache. He wrote a prescription for ear drops. In the directions he wrote, "Put two drops in right ear every four hours" and he abbreviated "right" as an R with a circle around it.
Several days passed, and the woman returned with her baby, complaining that the baby still had an earache, and his little behind was getting really greasy with all those drops of oil.
The doctor looked at the bottle of ear drops and sure enough, the pharmacist had typed the following instructions on the label: "Put two drops in R ear every four hours."