"The Patriot Act is anything but patriotic, it's a _____________."
Not the greatest example depending on your political view (sorry AuthRight), but I'm going off of the interpretation that the legislation named the USA PATRIOT Act purports itself to be something you would of course support if you were a patriotic person. Despite this, many believe the PATRIOT Act to be something entirely the opposite of patriotic.
So the term should describe something intentionally deceptive (perhaps to gain psychological influence). Homonym doesn't convey this intent. Malaprop describes a mistaken intent to a similar sounding word, but not a deceptive one. Contradiction in terms or Oxymoron describe a phrase that self-contradicts, but only one between the words it uses, not its external interpretation.
Single-word, phrases, and expressions all acceptable.