Dr. Kelso: Son, have you used drugs in the last 48 hours?
Patient: Oh no sir. Never use drugs.
Dr. Kelso: Because this shot you're about to get could kill you if it's mixed with narcotics.
Patient: Oh drugs! Yes sir, all the time!
Dr. Kelso: See? Waiting for the tox-screen, six hours. Frightening the bejeebies out of the local riff-raff, 10 seconds.