Select boomerang (upgraded) and then just lay down a key (must be metal) on your touchscreen. The key simulates a finger, so it will throw boomerangs automatic. Boomerangs are automaticly thrown in the direction of the boss so it will work no matter how many times the boss switches place. This glitch makes 500 money every two minutes. its really easy and you dont have to watch it because the screen thinks there is a finger on it so it doesnt turn standby.