A passerby thought this would be a great opportunity to get $200. So he entered the clinic.
Passerby: "Doctor, I have lost all taste in my mouth".
Doctor: "Nurse, please bring the medicine from box 22 and put 3 drops in the patient's mouth."
Passerby: "Yuck, that is Gasoline!"
Doctor: "Congratulations! You've got your taste back. That will be $100."
**********************
The passerby was annoyed and goes back after a couple of days figuring to recover his money.
Passerby: "I have lost my memory, I cannot remember anything."
Doctor: "Nurse, please bring medicine from box 22 and put 3 drops in the patient's mouth."
Passerby: "Oh no you don't, that is Gasoline!"
Doctor: "Congratulations! You've got your memory back. That will be $100."
**********************
The passerby leaves angrily now having paid $200 and comes back after several more days.
Passerby: "Doctor, my eyesight has become weak and I can hardly see!"
Doctor: "Well, I don't have any medicine for that, so here's your $200 back." (However, it is only $100).
Passerby: "But this is only $100."
Doctor: "Congratulations! You got your vision back! That will be $100."