“Jumping the shark” basically refers to a “publicity stunt,” when an entity, artist, or organization goes too far to maintain popularity or attention.
The term originates from the television series Happy Days, which was arguably the most popular American show of the 1970s and ran until the mid 80s. There was an episode in 1977 where an iconic figure from the show–Fonzi–is water skiing and jumps over a shark. Since then, the action has largely been seen as ridiculous and “over-the-top,” something that illustrated a moment where the show declined in quality (though it didn’t actually decline in popularity until years later).
“Jumping the shark” has become part of the American English lexicon.
Here are some possible uses:
I used to love the professor’s unusual demonstrations to illustrate the course material, but when he brought in a clown last week, I really felt like he jumped the shark. Now it is hard for me to take the course seriously.
My roommate used to wear unusual t-shirts because that was her style, but when she started getting attention from it, she started purposely finding more and more outrageous t-shirts before eventually making outlandish one’s herself. The one she wore to the party was just too much for me. She really “jumped the shark” with that wardrobe choice.
I was originally considering attending a different University. To be honest, this wasn’t my first choice. But when I was on tour at the other University, they kept on incorporating the mascot. At first, it was cute and humorous. But when I was trying to get a good view of the library and the mascot did a cartwheel in front of it, I felt like they “jumped the shark” and I was just plain fed up. I like silliness and fun, but I did not want to deal with an atmosphere like that for four years.
Watch the original jumping of the shark yourself and see what you think: https://www.youtube.com/watch?v=Tk_y_r5cXZs