I think they key to the quote is Jay Shermans' first quote where he says 'Camus can do but Sartre is Smartre', homer tries to one up him with 'Scooby do can do do but Jimmy Carter is smarter'. Jay Sherman was talking about philosophic rivals Albert Camus and Jean Paul Sartre, homer was making an absurd reference to Scooby Doo and President carter. In the episode patty and selma laugh at Jays remark and say 'how droll', when homer says his quip, no one says anything and a tumbleweed drifts by. In short, homer is dumb.