“I haven’t done this since I was 21,” Channing Tatum was overheard exclaiming as he tipped back shots with friends to celebrate his latest film, “Side Effects,” at Stone Rose Lounge. The hunk joked of his brainy Steven Soderbergh thriller, “It was fun for me . . . I got to play someone who went to college, for once.” Also at the Thursday Cinema Society screening, hosted by Michael Kors and Open Road Films, were Rooney Mara, Jude Law, Matt Damon, Michael Douglas and Catherine Zeta-Jones.