From Starbounder - Starbound Wiki
Thinking Cap is a costume hat. It has a very rare chance of being found in chests throughout the game.
It was a player submission in the Create-a-Hat Contest held on the official forums, and selected by developers to be added to the game.
- Perturbed Koala: Added to game files
- Cheerful Giraffe: Implemented, changed appearance, changed rarity from 'common' to 'legendary'