You get this for getting 15 coins.
I'm more of a fan of text guides, so here's the location of all thirty coins in text:
Behind the firefly after you get the apple
Throw the bone back into the village
Behind the second pillar
Lift the dragons tail up, under the dragons tail near the background
In the dragon's stomach, click the 2nd blob from the right on the ceiling. This will cause the dragon's toenail to lift reveling the coin
In the dragon's stomach, on the top left of the screen the coin is just visible
When you are picking up the club on the far right, there are two holes that you dodge by placing your mouse/finger on the opposite hole. Falling through both holes will get this coin.
To the left of the teepee
Click all of the stars
On the far right, behind the orange plant
On the Far left screen, to the right of the bird's beak, barely visible behind the trees.
Once you have all 4 raspberry music things, click the second one once, the third twice, and the last one 4 times so they look like stairs.
In the top right of the mouse hole. Move your cursor over the skull to click it
Become every wrong animal - Bear, Mouse, beE
B|B|B|B|M|E|M|M|M|M|B|E|E|E|E|E|B|M|M|M|B|B|E|E| -> Heads
B|B|M|E|B|B|M|M|B|E|M|M|E|E|B|M|E|E|B|E|E|M|B|M| -> Middles
M|E|B|B|B|B|B|E|M|M|M|M|B|M|E|E|E|E|E|B|M|E|M|B| -> Feet
(Copy and paste this into a blank text file to have the combos line up a little better)
Finish the level in one go (Have everything lined up perfectly, and then go through the mouse hole)
Finish the riddles in one go. Middle Right Left Left Middle
Once you have the magnifying glasses, look above the blue pedestal in the middle area
Play the pig app on the phone. Wait, close the ad that pops up, and then wait some more.
Pass the spinning puzzles with no mistakes.
Click the middle of the yellow 3 Monkey flag.
Shoot the earth on the part where you're shooting spaceships.
Behind the rocks in the first area.
In the first cave area take the light up to the top left tunnel.
In the second dark cave area, with the purple bugs, lead one of the red flies back up past the purple bugs to the original jellyfish to get this coin.
On the first screen, click the right snowflake twice to move the iceberg down enough to reveal this coin.
In the red area, behind a plant in the upper left of the screen.
In the green area, in the lower left, behind the metal ring in the foreground.
Open the cave door before you have the glasses. The glyphs you want to click are
Hit the flying squirrel with the bottle on your first try.
Using the glasses, to the left of the mountain in the sky when you exit the cave.