1. When Jon left BB4.

"jump the shark"

In a television show, to include an over-the-top scene or plot twist that is indicative either of an irreversible decline in the show's quality or of a desperate bid to stem the show's declining ratings.

http://jumptheshark.com/

BB first jumped the shark with Jade in BB3, made a brief recovery in the first four weeks of BB4 and has now jumped again. Will it recover?

I dont know if its jumped the shark but its dire IMHO . Think they just picked the wrong contestants. Needs some reviewing of ideas too (for example more HMs to start with)