The clear sign of a show about to "jump the shark" is when you see Ted McGinley join the cast.He was called the patron Saint of shark jumping because it seems as soon as he was cast the show began its downward slide and was never the same.Probably a coincidence because he was a nice guy and a decent actor,but that was his curse for a long time.according to the book JUMP THE SHARK.

Another sign is when the romantic tension between the male and female lead leads finally to marriage (MOONLIGHTING) or when there's a vacation involved or they have a "very special episode".

One more CLASSIC shark jump came when they introduced "cousin Oliver " on the BRADY BUNCH. It upset the entire tic-tac-toe dynamic of the.show.

That's just a few examples of " jumping the shark ".