Between the raindrops

I recently overheard someone use the phrase "here was a guy who could walk between the raindrops" to describe someone. What exactly does it mean, and is it common in some region?

I don't know if it's regional. I think it means the guy is really, really skinny.

Or it could mean he's very graceful.

I always thought it meant he had some sort of divine protection. Kind of like saying he could walk on water.