Nice Job Breaking It, Hero/Theater

"Little Sally: What kind of a musical is this?! The good guys finally take over and then everything starts falling apart?! Lockstock: Like I said, Little Sally, this isn't a happy musical. Little Sally: But the music's so happy!
 * Urinetown ends with the heroes triumphantly toppling the evil toilet monopoly and launching a new era of free urination. Only, as it turns out, the monopoly was right about the water shortage, the newly unrestricted flushing makes the town run dry, and almost everyone dies of thirst.

Lockstock: Yes, Little Sally. Yes, it is."


 * Hail Malthus!
 * The Wild Duck Nice job telling your friend his family's been lying to him all these years..
 * Wicked finds Elphaba listing her contributions to this trope in the song "No Good Deed".