Time to go back to high school with those throwing-rocks-at-birds contest. This time, however, do be careful, because if you let only one rock fall off the cliff, the neighbors will know and you, as well as your friends, are doom.
See if you can go for the highest possible score. Good luck!
Assets & Creation tools that I used:
Birds and stones assets from: Quaternius - http://quaternius.com/assets.html?i=3