S1·E12 Lucy and Her Electric Mattress

Lucy plans to surprise Vivian with a new mattress and a redone room while she's on vacation, but the electric mattress Lucy bought her malfunctions (it moves around the room when the motor is on) and Lucy is forced to return it. However, Vivian returns home early and has no place to sleep, so she and Lucy have to share the boys' bunkbeds for a night.