He had no patients
A Ducktor.
Everyone knows that you should see a doctor for an erection that last longer than 4 hours.
Both leave you waiting for the drop.
The Cat: because is a cat and a spider :) ... oh, wait.
Because he crossed the line
There's never a line for the bathroom.
Asked the patients. "You only have 24-hours to live." "And the really bad news " I should have told you yesterday.
He was losing his patients