What exactly constitutes "eating" a Devil Fruit? We've seen inanimate objects eat them, and it's barely been explained. I can understand an animal eating a Devil Fruit, but besides that, they don't seem too leniant.
For all we know, if a Devil Fruit falls from the tree, the ground has eaten it. What if it got under you fingernails? Would you aquire powers? What about the Gomu Gomu no Mi, which was kept in a box? Technically, the box has "eaten" the Gomu Gomu no Mi, so why didn't it turn into a rubber box?