Hydrophobic coating is without a doubt one of the most coolest inventions in recent years, but it's sometimes hard to imagine just how it can be useful. This is where GIFs like this one come in hand:
OK, I agree, having mustard fall out of your sandwich is not especially useful, but it already highlights a potential use: hydrophobic layer could ensure that you get all your mustard out of that damn plastic bottle! A significant part of mustard and ketchup remains stuck into bottles, and that could be solved through hydrophobicity. Physically speaking, hydrophobicity is the physical property of a molecule (known as a hydrophobe) that is seemingly repelled from a mass of water. In a stricter sense, there is no repelling force, it's just the lack of attraction.