Shrill giggles and the pitter-patter of tiny sock-swathed feet echo off the walls of Pump It Up, where lilliputian guests pinball through a metropolis of inflatable slides and bouncy enclosures. During glow pop-in play sessions, tykes frolic in the radiance of special lights, and in pirate-themed sessions, youngsters don costumes or just feel less self-conscious about the parrot permanently affixed to their shoulder. Small groups of ankle biters tear through the facility during private parties, plummeting down slides, scaling plush ladders, and bounding off of springy floors.