Loyal readers of this column are no doubt wondering why The Practice's Camryn Manheim is guest-starring on tonight's Two and a Half Men instead of Roseanne — who was initially tapped to play Berta's crazy sis. Well, here's the scoop: Although CBS insists the former sitcom superstar had a scheduling conflict, other sources tell me Rosie — who would have reunited with Men creator and ex-Roseanne scribe Chuck Lorre — bailed because "the script poked too much fun at her." Adds her rep: "She felt it [spoofed] her life during the Tom Arnold period." Scheduling conflict, my arse.