Often used by a mobster. "Hitting the matresses" is a term used during a mob-war. When two families or mobs are feuding, they battle it out by whackin' each other. "Hitting the matresses" is known as going into hiding. Usually finding an unknown, empty house, room, or appartment and sleeping on just a single matress.
It's getting rough, Sonny's already thinkin' of hittin' the matresses and we've only whacked a guy.
We need to hit the matresses before this shit gets outta' hand.