A man goes to see his doctor. 

The doctor asks what is wrong and the man says, "Doctor, I think I'm a moth."

To this the doctor responds, "You think you're a moth? Well I don't think you need a doctor. Sounds like what you need is a therapist." 

"Yeah I know," replies the patient. "I was on my way to see a therapist, but I came in here because I saw your light was on."