SPROING. That's the sound of a guest getting air in one of AirHeads' trampoline arenas, whose bouncy walls and floors let visitors break free of gravity for a few blissful seconds. Guests can ricochet off springy surfaces during fast-paced games of dodge ball and volleyball, simply fly into the air for the fun of it, or train for a bouncy future when all surfaces will be made out of recycled rubber. After each bounce session, they can cool off with video games in the AirCade or refuel at a café that serves pizza, wraps, and salad. Each location also hosts group events and bounce-centric birthday parties, as well as fitness classes whose low-impact aerobic moves can burn up to 1,000 calories an hour.