Several thousand Facebook fans like “Chicago.” A few weeks ago, the Broadway tuner liked them back.With old-school Broadway keen to explore the marketing benefits of new-media social networking, “Chicago” aimed to widen its network of friends with a promotion that gave away every single ticket of the Jan. 30 performance to Facebookers. A free ducat was offered to every Facebook fan of the show who could get 10 Facebook friends to like “Chicago” too. The initiative proved so popular that about six hours after the offer officially began, the dedicated app was so overloaded it had to be shut down. According to producer Barry Weissler, the whole endeavor cost around $100,000, given the forfeited ticket sales for the Sunday matinee as well as the food vans, celeb appearances, emcees, extra staffing and other amenities that were trotted out for the perf. It’s an unusual way to spend a chunk of marketing coin. “If we were talking about this seven years ago, a print ad would of course have been the way to go,” says Sara Fitzpatrick, the director of interactive media at SpotCo, the ad agency that handles “Chicago.” But with the declining influence of print on Broadway box office, producers are more willing shake things up. SpotCo topper Drew Hodges notes that the formerly print-heavy campaign for “Chicago” shifted more to online in 2009, and in the year following that move, sales at the tuner were up by 14%. The Facebook perf functioned as a show-specific consumer loyalty program, rewarding the fans most likely to help keep the tuner afloat with repeat biz. Prior to the promo, “Chicago” had about 10,000 fans on Facebook; now it’s almost up to 20,000. Plus, there were all those status updates, tweets, FourSquare shout-outs and other pings that hit the Web following the perf. “There was an awful lot of communication going out there,” Weissler says. “I must have gotten quadruple the exposure.” Buoyed by the success of the event, the producer says he’s considering a similar event for the show’s London outpost.