Roll Some Heads

You'll know that you have achieved this achievement when a Gold Coin drops from a zombie. The easiest way to get this is to wait for a wave of zombie horde and then rolling a Wall-nut at the lead zombie, or preferably by leaving a few zombies from before the wave alive long enough to bounce a Wall-nut off of them too.

You will have an increased chance of achieving this in Wall-nut Bowling 2 because there are more zombies there, do it during a huge wave and in front of a Backup Dancer and 3 zombies would be instantly hit.

Just make sure that there are a lot of zombies when you aim for this one.

Note: Neither Explode-o-nuts or Giant Wall-nuts will count for this achievement as using these will not give you any coins or count as a combo.

Trivia

 * The name of this achievement could be referring to the Wall-nut as a "head" and that it's rolling.