Got the snowman now: Get the medium ball in the chimney, all by itself, then fire away all your Santas off screen until there are none left. If you then hit the medium ball 2-3 times, hard, it will roll away and get stuck between the chimney and ramp. It doesn't work if there are any Santa's piled up at the ramp. I've been able to do this with about ~50 Santas three times now.
(hey, they're making us work on Christmas Eve, why not?)