It's first grade, Spongebob Share definition Flag A phrase commonly said to someone who doesn't know, or doesn't seem to know something very basic or elementary. "What do you mean you don't know how to roll a joint? It's first grade, Spongebob!" It's first grade, Spongebob by Mäynard Lankford February 14, 2012 Get the It's first grade, Spongebob mug.