My Doubleminusbad Newspeak Grammar

What is the opposite of "Doubleplusgood" (and should doubleplus have a hyphen)? I have been using "Doubleminusbad", since bad is the opposite of good and minus is the opposite of plus. However, in correct "Newspeak" the opposite meanings of words are removed as redundant, so "bad" became "ungood".  And I have been using minus and doubleminus in the same way grades and credit ratings do. For example,  F- is worse than F+.  However, in correct Newspeak, plus and doubleplus are intensifiers (very good is plusgood and excellent would be doubleplusgood). So the correct opposite of "Doubleplusgood" should be "Doubleplusungood". But, I think I'll keep using "Doubleminusbad" just to honk off the Thought Police (Bureau of Grammar Crime Division).