Gentle Reader ExGeeEye asks: "What does it mean 'working out with a water bag'?"
Bugscuffle County does not supply our inmates with weight equipment.
Matter-of-fact, we don't supply much more than a basketball and a couple of racquet balls.
Inmates, however, are nothing if not adaptable. Given half a chance they steal garbage bags, fill them full of water from the showers, and use those in improvised weight routines.
Given that one gallon of water weights eight pounds, a 33-gallon garbage bag can be a fairly significant amount of weight.
Voila! "Water bag".