The phrase jumping the shark is used to describe a TV programme which has gone for too long, the quality of the programme has declined and the programme is being continued when it is felt the programme has reached the end of its shelf life and it is past its sell by date. Are there comedy programmes you feel that jumped the shark? This can apply to any kind of comedy programme.
In my view Only Fools & Horses jumped the Shark with 2001-2003 trilogy.