To unlock this achievement you first have to unlock Brianna by winning ten races in any mode.
Once you have her unlocked pick:
Papaya Grove>Avacado Roller
Game Mode must be Dragster
Then select Easy and number of racers does not matter.
In Dragster mode your Mega Juice Move is unlocked after a small countdown. Once it is availaible, click in the
and the achievement will pop soon after. The apple doesn't have to hit anyone for it to count, the achievement is simply for firing it.