In JJ Extreme territory, a girl wearing a harness is suspended from the ceiling by a rope and swings back and forth, her squeals carrying throughout the space. Elsewhere, her brothers also wear harnesses as they race one another, running toward a basketball hoop and hoping to make a shot before a bungee cord pulls them each backward across a soft, inflatable mat. Here at JJ Jump and JJ Extreme, each location sprawls over more than 4,000 square feet and teems with inflatable challenges and bouncing joy for children. JJ Jump’s jousting arena settles sibling rivalries in a civilized and laugh-filled fashion, and giant slides teach children about the effects of gravity and hair’s weakness against it as they safely soar toward the ground. Each facility also boasts a creative play zone that eschews bouncing for a while and is ripe with construction toys and a stage where children can let their imaginations run wild.