"Where exactly are you taking me, doctor?"
"To the morgue."
"But I'm not dead yet!"
"But we're not there yet."
"Where exactly are you taking me, doctor?"
"To the morgue."
"But I'm not dead yet!"
"But we're not there yet."
The humor is dark because the doctor is taking the patient to the morgue before they are even dead. It's playing on the literal meaning of going to the morgue and the fact that people usually go there after death.