No, it's a simile. An example of a synechdoche would be "All hands on deck," except in those rare cases when one is playing bridge on the deck of a ship and you want everyone to put all of their cards down.
One example might be " as tricky as a box of monkeys".Another example is "as dumb as a box of rocks".
it means that the box of rocks didnt listen anything and the person in this phrase is compared with box of rock
...a box of rocks. ...a bag of hammers. ...a fence post. ...a Dodo bird.
It means really dumb!
No
The oldest simile for 'as dumb as' is 'As dumb as a doornail'. Others include: As dumb as a wet noodle. As dumb as an unpowered computer. As dumb as a library with no books.
No. Box does rhyme with rocks, though.
boulder holder
rocks
because there dumb
boulder holder
brush In the American South we say "dumb as a box of hair"