I mean it's like an idiom used to denote the point in a television program's history where the plot spins off into absurd storylines or unlikely characterizations. These changes were often the result of efforts to revive interest in a show whose audience had begun to decline.
For example, like the 2008's Indiana Jones and the Kingdom of the Crystal Skull where he was hit by the blast of a nuclear weapon while hiding inside a lead-lined refrigerator in a desperate attempt at survival. The refrigerator is hurled a great distance through the sky and tumbles hard to the ground, while the structures surrounding it are utterly obliterated. A relatively uninjured Jones emerges to witness the mushroom cloud miles away. Some moviegoers found the absurdity of this event disappointing and reflective of the decreased quality of the series, thus the term nuking the fridge.
For example, like the 2008's Indiana Jones and the Kingdom of the Crystal Skull where he was hit by the blast of a nuclear weapon while hiding inside a lead-lined refrigerator in a desperate attempt at survival. The refrigerator is hurled a great distance through the sky and tumbles hard to the ground, while the structures surrounding it are utterly obliterated. A relatively uninjured Jones emerges to witness the mushroom cloud miles away. Some moviegoers found the absurdity of this event disappointing and reflective of the decreased quality of the series, thus the term nuking the fridge.