The Invisible Gorilla is a former attraction at the Sleaze Brothers Funfair. In Follow That Bird, Sam and Sid Sleaze present their "star" through the use of trick mirrors and the natural logic that "of course one can't see him, he's invisible." The Invisible Gorilla's stardom is shortlived, however. Once the Sleazes capture Big Bird, the incorporeal ape is replaced by the Blue Bird of Happiness.