The initial idioms of the letter N

not just a pretty face	not just whistling Dixie
not know A from a windmill	not know beans
not know beans about	not know beans about something
not know enough to come in out of the rain	not know from Adam
not know from nothing	not know (someone) from a bar of soap
not know if are coming or going	not know one’s ass from a hole in the ground
not know own strength	not know shit about something
not know shit from shinola	not know someone from Adam
not know the first thing about	not know the time of day
not know what hit	not know what to make of
not know where to turn	not know whether one is coming or going
not know whether one is coming or going and not kn	not know whether to laugh or cry
not know which end is up	not know which way to turn
not let the grass grow under feet	don't let the grass grow under one's feet
not lift a finger	Not likely