Matmos, an experimental-music duo, used plumbing for their performance at Dia Art Foundation’s Fall Gala. “They took a snake camera and put it 100 feet deep into a toilet, and then flushed glitter through it, all while playing electronic music from the sounds made by Dia’s plumbing,” says a spy. “I heard [fotog] Todd Eberle exclaim, ‘This is the craziest thing I’ve ever seen!’ ” The duo also used samples and live sounds they created by throwing metal pipes against the cement walls of the after-party space, Dia’s future home at 541 W. 22nd St., for guests including Leelee Sobieski, Amanda Hearst, Sarah Hoover and Kate and Andy Spade.