A brown paper bag.
A brown paper bag went to the doctor complaining of feeling unwell.
The doctor took a blood sample and told the bag to
come back the following week.
When the bag arrived for his follow up appointment, the doctor said, “I’m afraid I
have some bad news. The results of your blood test indicate
that you have hemophilia?”
“How can I possibly have hemophilia? I’m a brown paper bag!”
“Yes,” replied the doctor, “but it seems your mother was a carrier.”