Wrong Thing

Wrong Thing n.  A design, action, or decision that is
   clearly incorrect or inappropriate.  Often capitalized; always
   emphasized in speech as if capitalized.  The opposite of the
   {Right Thing}; more generally, anything that is not the Right
   Thing.  In cases where `the good is the enemy of the best', the
   merely good -- although good -- is nevertheless the Wrong
   Thing. "In C, the default is for module-level declarations to be
   visible everywhere, rather than just within the module.  This is
   clearly the Wrong Thing."