S3·E56 Madeleine Bordallo

Stephen is unhappy at the fact that Stephanie Colburtle The Turtle did not win The Great Turtle Race, after being bested by another turtle named Billy. He claims Billy is a male, and demands a re-race. (After explaining that one can tell the sex of a turtle by the concavity of its plastron, Stephen says that he checks the plastron on "all [his] dates, and if it's not concave, [he is] outta there."