Sentence:  "Happy Days" infamously <WSD>jumped the shark</WSD> when Fonzie literally jumped a shark on water skis. "I Love Lucy" <WSD>jumped the shark</WSD> when Lucy and Ricky moved to the suburbs. "The Brady Bunch" <WSD>jumped the shark</WSD> when Cousin Oliver moved in. 
Meaning of the word marked with <WSD> tags:  To undergo a storyline development which heralds a fundamental and generally disappointing change in direction.