What is the legal definition of "yummy"?

So I'm sitting here making some hot cocoa and I notice that the box says "Guaranteed yummy." Now, I don't doubt that they would refund my money if I was not satisfied with the product, but if I did need to take them to court, what would be the legal definition of "yummy"? Would only my opinion count, or would I need a consensus of people saying that they don't find it to be "yummy"? Could the court find that the cocoa is "yummy" even if I think it tastes like dirt? By the way, I just tasted it and it's okay, but it's a far cry from what I would call "yummy." Maybe my "yummy" standards are too high.