Rejects The Organ

A prostitute goes to the hospital to visit a colleague who is about to have a heart transplant.

She's worried about the friend so she asks the doctor, "I'm worried about my friend, Doc, what if her body rejects the organ?"

The doctor says, "Well she's 36 years old and healthy. How long has she been in business?"

"She's been working since she was 19 years old but what does that have to do with anything?"

"Well she's been working 17 years and hasn't rejected an organ yet!"