In "The D in Apartment 23", Stewie decides to go along to the Quahog University Library to avoid having to do sad, one-woman shows like Meg in his future, leading to a cutaway gag of Meg singing "I Love Trash" while dressed as Oscar. When Lois questions whose genes she received, she points out to Peter that he is wearing a garbage bag as a cape. They are both quieted by Oscar, who notes that Meg is doing an excellent job in the role.
In "Boy's Best Friend", Peter, Cleveland and Quagmire take Joe's classic car for a drive and crash into a pile of trash cans, killing Oscar the Grouch in the process. Before he dies, Oscar requests Peter tell his ex-wife to 'go fuck herself' which Peter notes is on-brand for Oscar.