Party hat meta!
The achievement is a funny story. Matheus thought it would be nice to have it in the game, so he stopped everything he was doing at the time (which was objectively more important since it was the last day of the jam) in secret.
Lo and behold, he took a screenshot of the steam achievement UI and pasted our character on top of it.
I was not amused. So I also made him add chickens in the game.