Which one is Pink, which one is Ain ?
The original intent was for the eraser to be named Pink (he is, after all, pink), and the pencil to be Ain’t (because he ain’t pink). There’s another school of thought that says that the eraser should be called Ain’t, since he erases stuff. I guess that doesn’t explain why the pencil would be called Pink, though…. Anyway, the official line is that the eraser is Pink, and the pencil is Ain’t.
