Morris walks into a doctor's office and says, "Doc, you gotta help me. I've got a constant erection. At first it was fun, but then it became painful and embarrassing."
He takes down his pants, and his hardon is sticking straight out. The doctor looks at it for a minute, then whacks it with two fingers. A little bug jumps off, scurries away and just like that the hardon goes right down.
Morris says, "Gee, Doc, that's great. How much do I owe you?"
The doctor says, "Help me find that bug and you don't owe me a thing."