According to the third law of motion, the velocity of a child remains constant until they are acted upon by an external slice of pepperoni pizza. Help contain kids' overactive atoms with today's Groupon: for $20, you get five walk-in kids' play sessions at Flabbergast (a $44.75 value).
Flabbergast occupies jumpy juveniles with an indoor kingdom of colorful slides and cushy trampoline-floored rooms. Set kids loose to ricochet off the walls of six giant inflatables, or accompany them to the giant climbing fortress to teach how our mountaineers practiced feudalism. Elsewhere, Flabbergast's huge arcade area plays host to more than 50 games, and the café builds up playtime energy with a menu of snacks. All children younger than 18 must be accompanied by an adult; in between peeking at their youngsters from the lounge area, chaperones can revel in grown-up comforts by sinking into a plush chair, watching the flat-screen TV, browsing on the free wireless Internet, or comparing driver's-license photos.