This Memorial Day weekend, if you see a woman on the street or the subway laughing her head off while reading Jennifer Belle‘s new novel, “The Seven Year Bitch,” it might be an act. Belle, the best-selling author of “Going Down” and “High Maintenance,” usually isn’t at a loss for readers. But this time around she’s gotten super-entrepreneurial. After receiving more than 500 résumés, she auditioned 100 actresses and hired 40 to fan out across the city and burst out laughing in public while reading her book. The actresses are being paid $8 an hour, a source said, and will hit high-traffic areas like the Red Steps above the TKTS booth in Times Square. Belle says it’s like in India where people hire professionals to cry at their loved ones’ funerals. “I’m hiring actors to laugh at my book,” Belle explains. “Publishing is no laughing matter these days.”