Cousin Oliver 

a jinx played by actor Robbie Rist. Cousin Oliver was added to the cast of "The Brady Bunch" the last six episodes of the fifth season. The Brady kids thought he was a jinx because he was accident prone. Then the show was canceled. He really was a jinx.

Every time Joe shows up something bad happens. He is worse than Cousin Oliver.

Cousin Oliver by Jefgg September 21, 2013

pull a cousin oliver 

when a TV show adds another younger character because the previous younger character(s) on that show has become too old and outgrown their cuteness.

Term originates from when The Brady Bunch introduced a new character named cousin oliver (in what turned out to be the final six episodes of the show) because all the cute kids grew up.

when raven - symone was added to the cast of the Cosby Show because Bill thought Keisha outgrew her cuteness

pull a cousin oliver example numer dos: Malcolm in the middle, when Lois got pregnant around the 4th season.

pull a cousin oliver by I'M BATMANNNNNNNNNNNNNNNNNNN!! August 30, 2012