The phrase "You're Wet" is the clincher. In American English, "You're wet" is an observation of fact. In British English slang, "You're wet" can also mean you are feeble, pathetic, or boring. But in the context of a grandmother? It usually means literal water. And that literal water always has a story.
Today, when I see her, I try to be the one holding the umbrella. I try to notice the small "rains" in other people's lives and ask, "Are you wet? Let me help." -ENG- My Grandmother - Grandma- You-re Wet