Pokermen

"Here's the skinny"...this is a very old fashioned way of saying "I'll tell you everything." During world war two until the late 1960's, military orders in the Marine Corps were copied on paper that resembled the skin of an onion. It was extremly thin and fragile, and translucent in appearance.
Whenever a marine would want to know the orders, he'd ask "what's the skinny?" At least, that's according to the internet...