I've seen all of these happen, and if you've been a fairly regular watcher of television over the last 10 or 20 years, you probably have too... If you really think about it, TV is ridiculous! (duh!) ;)
Chuck Cunningham syndrome:
Chuck Cunningham syndrome is a term of criticism, applied when a regular character (ie: main character, supporting character, recurring character) in a television series is removed with little or no explanation.Jumping the shark:
The term derives from the Chuck Cunningham character in the American series Happy Days. Chuck, the oldest of the three children in the Cunningham family, initially appeared in the episode "Love and the Happy Days" (in the show Love, American Style), which served as the pilot for what became the Happy Days series. However, in Happy Days Chuck appeared as a superfluous character (usually on his way to basketball practice). He was written out of the series at the beginning of the second season with the explanation that he was going to college. After the second season, he was never mentioned again; subsequent episodes referred to the Cunninghams as having two, rather than three, children.
Jumping the shark is a metaphor that has been used by US TV critics and fans since the 1990s to denote the tipping point at which a TV series is deemed to have passed its peak. Once a show has "jumped the shark," fans sense a noticeable decline in quality or feel the show has undergone too many changes to retain its original charm.Cousin Oliver:
The phrase was popularized by Jon Hein on his website jumptheshark.com. It alludes to a scene in the TV series Happy Days when the popular character Fonzie, on water skis, literally jumps over a shark.
Cousin Oliver is a jargon used by TV critics when the creators of a TV show decide that the addition of a cute child actor to the cast will improve the ratings of the show, or as a replacement for child cast members that have grown up since the show started.Fonzie Syndrome:
Fonzie syndrome is a phenomenon on TV programs in which a character that had originally been a one-off character or a supporting cast member becomes a/the central and/or most popular character on the show. The term comes from the American sitcom Happy Days, in which the character of Arthur "The Fonz" Fonzarelli (played by Henry Winkler) started out as a minor, fringe character but quickly evolved into the focal point of the series.Retcon:
Retroactive continuity is the adding of new information to "historical" material, or deliberately changing previously established facts in a work of serial fiction. The change itself is referred to as a "retcon", and the act of writing and publishing a retcon is called "retconning".