Okay, I finally got this one. On the Moustache world, on the bottom row, go over seven squares, to the Madagascar square that has both brown and red land masses on it.
This one has two bouncy balls in it and and 6 tanks. The strategy that worked for me, thanks the below video on Youtube is to bounce the rock back to the king's head using the lower bouncy ball twice. Then throw the rock over to hit the bottom of the higher bouncy ball in order to take out some tanks.
Hopefully you will get at least 3 tanks in order to get another golden rock, which would be the third.
Then hit the king in the head again twice by using the lower bouncy ball. The fourth time the rock hits the king will not only kill the king, but give you the Golden Five achievement.