if a person or a country is armed to the teeth, they have many weapons.

We walked past a group of soldiers, armed to the teeth.

• not judge a book by its cover
• not know beans about
• not know beans about something
• not know from Adam
• not know if are coming or going
• not know if you are coming or going
• not know someone from Adam
• not know the first thing about
• not know the first thing about something
• not know the half of it
• not know the meaning of the word
• not know what hit
• not know what hit you
• not know where to put
• not know where to put yourself
• not know where to turn
• not know whether are coming or going
• not know whether to laugh or cry
• not know whether you are coming or going
• not know which way to turn
• not let the grass grow under feet
• not let the grass grow under your feet
• not lift a finger
• not long for this world
• not look a gift horse in the mouth