"Brian & Stewie"
Season 8, Episode 18

Stewie purchases a Thom Browne cardigan from the descigner's Fall 2009 collection. After dropping over $3,000 on the piece, he decides that he "loves it," but "it's too much" and he makes up his mind to return it. When he tells Brian how much he paid for it though, Brian calls him "a pretentious moron" for spending that much on a cardigan.