Theme 21-6 is the 6th level of the second episode of the world Bad Piggies, in the game Angry Birds.
Shoot the Yellow Bird at the string holding up the stone brick. The Yellow Bird's corpse should land on the peice of rubber and bounce onto the stone on the top of the level. This should be enough to eliminate all the pigs in the level. Also, you should get 30000 points from the remaining Yellow Bird, and 2 Red Birds.