Final answer:
The description of the Cocos t-shirt designed by a character named Joe cannot be provided without additional context or reference to specific source material.
Step-by-step explanation:
Since the information provided does not refer to a general knowledge topic, specific educational subject matter, or recognized cultural phenomenon, it appears to refer to a piece of fictional or private information. The details of Joe's designed Cocos T-shirt are not common knowledge and would depend on the context provided by the source material (a book, TV show, movie, etc.) in which this character, Joe, exists. As such, without additional context, providing an accurate description of the Cocos T-shirt that Joe designed is not possible. If the question is referencing a specific piece of literature or media, please provide more details or clarify the source material.