opb:
I suppose if a smack of boxes would be a small boat with a cargo of boxes, then a box of smacks would be a very big box, perhaps a shipping container, full of small boats. I don't know why the worst behaved boy would want one, but the worst behaved buoy might.
Now be serious, you are just playing with words. A box of assorted smacks seemed a possibility. We never quite knew what was kept in that large cupboard behind the blackboard! Anyway to have even been nominated once as the worst behaved boy in the class was quite an honour for me! Not often I am nominated for anything!