in the show Happy Days, fonzi jumped a shark in the latter shows.
it was stupid and the show died shortly after that.
I like their theory that Sesame Street jumped the shark when Elmo came on board.
Up until then all of the characters had an edge to them...Oscar the Grouch, Cookie Monster, the Count...then they brought in this loveable little cuddly furball.
In todays PC world, the Cookie Monster is no longer the cookie monster...childhood obesity and all.