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.

When you're being horny (especially around friends) and as a result shame ensues.