You get this for getting the apple in the first area.
From the screen with the apple:
1) Go left and click the gate on the left side to get the bone.
2) Go back to the tree, and try to throw the bone at the snake.
3) Go to the right screen, and pick up the fork. Go use the fork on the snakes tail.
4) Go back and get the bone where you dropped it. Use the bone on the apple.
Enjoy the weird trippy cutscene and your first achievement for the game :)