medical phenomenon

Just now I looked down at my fingers, and noticed that they appeared to have a blue, grey-ish hue. Flipping my hands over, I noticed with growing alarm that my knuckles were, indeed, a peculiar deathly shade of blue. Immediately I thought of the symptoms of meningitis or sepp-whatever and couldn't remember if turning blue was on the list - "Why did I pitch that helpful calendar!! I could have meningitis and now I can't know!"

Then I washed my hands.

And remembered that my new-ish jeans have this special indigo dye that transfers if say, you shove your un-mittened hands in them.

Ridiculous.