Cinematic equivalent of the TV term "jump the shark." It is used to refer to the moment in a film series that is so incredible that it lessens the excitement of subsequent scenes that rely on more understated action or suspense. Such moments are felt to mark the beginning of a low point in the quality of the franchise, as it attempts to explore more absurd avenues. "Nuke the fridge" is a reference to a scene in Indiana Jones and the Kingdom of the Crystal Skull wherein the title character incredibly survives a nuclear blast by climbing into a lead-lined refrigerator. The fridge is blown hundreds of feet into the sky, and, when it lands, Indiana Jones opens the door and walks away completely unscathed and apparently unaffected by any radiation sickness that would surely result from being in such close proximity to a nuclear blast.
The phrase was coined by disappointed IMDB users on the Indiana Jones 4 message board at that website who believed that the franchise had, in fact, nuked the fridge, and that this scene in particular marked its turn for the worse.
"Man, when Peter Parker started doing the emo dance in Spider-Man 3, that franchise officially nuked the fridge."
"Aliens?! Oh God, did Indiana Jones just totally nuke the fridge or what?"