by/through the back door - not in a direct, official, or honest way.

The minister dismissed suggestions that the move was a back-door attempt to introduce national identity cards.

• need to have your head examined
• need your head examined
• need your head examining
• neither here nor there
• nerves of steel
• nest egg
• never a dull moment
• never darken door again
• never darken your door again
• never hear the end of it.
• never hear the end of it
• never live down
• never live something down
• never mind
• never mind someone
• never mind something
• never-never land
• never say die
• Never say die.
• never say never
• Never the twain shall meet.
• never the twain shall meet
• new ballgame
• new blood
• new broom