Recreational Vehicle. Like a big fat camper with beds, bathroom, fold out tables, and stove. The biggest name brand is Winnebago. People take these on vacations if they want to have a real comfortable ride where the family can sleep, play cards, etc. while they drive, and if they don't mind using a LOT of gas. You can climb up a ladder on the back and sunbathe on the roof. The same people who own RVs are likely to have rec rooms in their houses.