I can cure pneumonia

A man went to see his doctor because he was suffering from a miserable cold.
His doctor prescribed some pills, but they didn't help.
On his next visit the doctor gave him a shot, but that didn't do any good.
On his third visit the doctor told the man, "Go home and take a hot bath. As
soon as you finish bathing throw open all the windows and stand in the draft."
"But doc," protested the patient, "if I do that, I'll get pneumonia."
"I know," said the doctor, "I can cure pneumonia."