Where did the phrase your such a goofball come from?

The phrase "you're such a goofball" is a modern colloquialism that doesn't have a specific origin point. It's likely a combination of several factors:

* "Goof" as a slang term: "Goof" has been used as slang for a mistake or a foolish action since the early 20th century.

* "Ball" as a playful term: "Ball" has often been used to refer to something fun, lighthearted, or carefree.

* Combining the two: The combination of "goof" and "ball" likely emerged organically as a way to describe someone who is silly, clumsy, or playful in a lovable way.

There's no single definitive source or origin for this phrase. Its popularity likely stemmed from its natural and easy-to-understand meaning, making it readily adopted into everyday language.