During the 1969 season of Sesame Street, Oscar the Grouch was orange. Orange Oscar only lasted one season before he became the green Oscar we all know and love. The clip below shows an orange Oscar singing “I Love Trash.”
If you want to know why Oscar’s color changed, there are numerous explanations, such as he would not be such a light color if he lived in garbage or the puppet was not comfortable. My favorite explanation is a variation on the former and comes from the YouTube comments section.