A Chinese doctor can't find a job in a hospital in the US, so he opens a clinic and puts a sign outside that reads "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 for taste.
Doctor: Nurse, bring medicine from box No. 22 and put 3 drops in patient's mouth.
Lawyer: Ugh, this is kerosene.
Doctor: 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 can't remember anything.
Doctor: Nurse, bring medicine from box No. 22 and put 3 drops in his mouth.
Lawyer:{annoyed} This is koresene. You gave me this last time for restoring my taste.
Doctor: 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.
Doctor: Well I don't have any medicine for that, so take this $100.
Lawyer :{staring at the note} But this is $20 not $100.
Doctor: Congrats, your eyesight is restored. Give me $20.