What kind of slang will you find at the gym? The old standby, jacked, meaning “muscular,” may derive from the lifting motion of a car jack. January joiners are those well-meaning souls who make new year’s resolutions to get in shape, and stop showing up a week later. Cardio queens are the ladies in fancy sweatsuits taking a leisurely stroll on the treadmill while reading a magazine. This is part of a complete episode.