Here is the full list of all 20 Guano achievements.
You unlocked all the game's concept arts!
You destroyed Food Inc. buildings for Krakatoa.
You released a nuclear poop on Pohemeda Islands
You defeated Evil Guano.
You pooped on Seagullini. That'll teach him
You delivered the "secret ingredient" to Kevin
You delivered the "secret ingredient" to Dunga.
You defeated Kevin, again!
You super screamed at a human
You helped Dr. Squawkson test her bouncy buoys.
You started a boatruck chain explosion
You got hit by a boatruck multiple times
You bullied Shy Gary for Seagullini
You defeated Kevin!
You helped Dr. Squawkson test her directional buoys.
You pooped on a human for the first time
You pooped 25 times
You farted 3 times while your poop was reloading
You opened the game!
You hit the same donut billboard as in the intro