When the LaBruzzo family pulled its second Chubby's restaurant out of the Barclay building, it took a couple of years to get the new location -- a free-standing box with a spacious parking lot -- open and running. But the new place is a year old and has really caught on: It's busy day and night. The place stays open 24 hours every day except Monday (when it shuts down from 2 p.m. until 6 a.m. Tuesday for its weekly cleaning). It's done up like a 1950s snack bar, complete with tableside juke boxes and photographs of "American Bandstand"-era pop stars. Late at night, though, it's more Rocky Horror Picture Show than Rock and Roll Hall of Fame. On weekends, the post-midnight crowd ranges from waifish pierced and tattooed youngsters to suburban couples to bulked-up and stylishly coifed disco boys who have whirled right off of a dance floor and into a leatherette booth. Chubby's signature hamburger is "The Big One," which becomes a double entendre after midnight. The menu is packed with possibilities, so if you wake up at 3 a.m. craving a fried meatball sandwich, a cinnamon roll and a slice of gluey coconut cream pie, it only requires a drive to Midtown. And cash, no credit cards.