A Chinese Doctor can't find a job in a Hospital in the US, so he opens a clinic and puts a sign outside: 'GET TREATMENT FOR $20 - IF NOT CURED GET BACK $100!' An American lawyer thinks this is a great opportunity to earn $100 and goes to the clinic.

Lawyer: "I have lost my sense of taste."
Chinese: "Nurse, bring medicine from box No. 22 and put 3 drops in patient's mouth."
Lawyer: "Ugh. this is kerosene."
Chinese: "Congrats, your sense of taste is restored. Give me $20."

The annoyed lawyer goes back after a few days to recover his money.
Lawyer: "I have lost my memory. I cannot remember anything."
Chinese: "Nurse, bring medicine from box no. 22 and put 3 drops in his mouth."
Lawyer (annoyed): "This is kerosene. You gave this to me last time for restoring my taste."
Chinese: "Congrats. You got your memory back. Give me $20."

The fuming lawyer pays him, and then comes back a week later determined to get back $100.
Lawyer: "My eyesight has become very weak I can't see at all."
Chinese: "Well, I don't have any medicine for that, so take this $100."
Lawyer (staring at the note): "But this is $20, not $100!!"
Chinese: "Congrats, your eyesight is restored. Give me $20"