What if the sign in fact asked “What If Corn Knew Its Density” instead? Somebody or something has to know the density of corn. I don’t suppose most corn knows, what with it generally not being at all sapient and being involved in matters of density really only when it’s tossed into water. And at that point it probably has more urgent considerations than density qua density. I’m thinking, anyway. At least you could have a movie about some corn hero rising up to change its density and have that be a meaningful concept.