Time sneaks up on you like a windshield on a bug. - John Lithgow
Happiness often sneaks in through a door you didn't know you left open. - John Barrymore
Happiness often sneaks through doors you didn't even know were open - - Unknown (to me :P)
Deception sneaks in through the window of pride. - Evinda Lepins
Most of the bad guys in the real world don't know that they are bad guys. You don't get a flashing warning sign that you're about to damn yourself. It sneaks up on you when you aren't looking. - Jim Butcher