"When he got up this morning he took an aspirin and some vitamins, then he took pills for his ulcer and pills for iron. then after some cough medicine he took drugs for a cold, and when he lit a cigarette there was some kind of explosion"
"There seems to be some sort of round, shiny obstruction - no, that's the doorknob!"
At first glance i thought that this cartoon was implying that the man was dumb as a doorknob. Upon a second look i think it is mearly implying that he is empty headed