Physicists have determined that the best way to subdue wall-bouncing photons is to let them loose until they need a nap. Apply the latest scientific findings to your kid’s playtime with today's Groupon: for $18, you get four two-hour wristbands, one large pizza, and four soft drinks at That Fun Place in Greenfield (a $65.85 value). Part arcade, part black-light adventure zone, part playground, and part pizza parlor, That Fun Place caters to the fluctuating tastes and attention spans of adults and the children who own them. Guests of all ages can fuel fun tanks with soft drinks and a pizza that is customizable with up to four toppings before launching into their two hours of limitless, un-groundable activities. Escape the twists, tubes, and ball-filled oubliettes of the three-story indoor playground, stalk through black light-sensitive rainforests in a round of laser tag, or practice for an intergalactic driving test with a whirl in the cosmic bumper cars. If the indoor amusements aren't enough to fill your quartet's fun quota, That Fun Place also offers outdoor attractions such as a train, a minirollycoaster, and a flying banana ride for days not hindered by rain, snow, or actual flying bananas.