A ginormous box of coal! And it's not even really theirs, they have to share it with six other naughties.
They snubbed the gift, or at least that's the story they're sticking to. The green stains on the bottom of their feet (Gazzles' white paws in particular) from the non-toxic tempera paint powder I used to dye the sand betray them, though - they're clearly going in there when I'm not around. Smart as they can be, they didn't realize there was a "silent alarm" built into the gift to tell me when someone had been secretly playing with it
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I laughed out loud when I read that! I can just picture them walking around with glow in the dark paws!!!