Wave Goodbye - S6-E5
Plot hole: Dr. Mike and Daniel are discussing whether Princess Nizamoff is a fake or not, considering all the voices from the dead she performed during the séance. Yet Mike totally forgets that Mizamoff addressed her former medical professor in grave detail. Something the Princess would not have known otherwise.
Plot hole: In the ending scene, Mike has a probable concussion from her fall, so Sully keeps her awake to prevent her slipping into a coma. They talk all night, reminiscing as Mike experiences periodic pain spasms. Their talk ends with discussion over them having another child, and then they instantly engage in an intimate moment, which would be impossible, considering her condition, and without further checkup from another doctor. Sometime later she is suddenly feeling 'cured', and they return home.
Answer: A Cooper was someone who made various things out of wood including wooden caskets and even barrels.