The MOMA PS1 Warmup party this past Saturday felt like an adult version of the Chuck E. Cheese ball pit.  The quintessential NY summer event was held in the museum's large segmented yard, where partygoers had a multitude of play options --  bopping around on boncy balls, lounging on hammocks, or lolling around on the sand-covered ground. A DJ set from Animal Collective, whose latest album Merriweather Post Pavilion is about as fun-in-the-sun as you can get was fine; much more ecstatic and fun was the Brooklyn duo, Blondes.  The show-stealing architectural installation, interconnected swaying poles with grid-nets and bouncy balls, also provided much for the increasingly inebriated crowd, who danced as the sun set over Long Island City.