The opposite of the suntan that lazy people get sitting on the beach, when you're working your butt off in the studio until the early hours of the morning.
Typically blamed on the winter months, by people who work just as hard in the summer & don't see daylight from one year to the next.
They: "Why don't you go outside & get a little sun on your bones"
You: "It's my studio tan. I've been working on it all summer"
They: "Er... I thought a tan made you darker"
You: "Dude, I'm in the dark Dude. I am the darkest of them all."