Wet is a relationship between a surface and a liquid, based on the liquid's viscosity and adherence to the surface.
Where this came from, and how the conversation got this far without this point being made... I don't know
A random online dictionary says it means "(fully or partially) covered with water" and I hereby declare that this means that only singular water molecules are not wet.
Jokes are hard and sometimes they don't make the splash we intend.