After hearing from Pink is the New Blog that Britney Spears is slated to guest-star in an episode of How I Met Your Mother, we fear that the CBS producers behind the idea haven't had the pleasure of sitting through her 2006 appearance on Will & Grace. W&G gave her the one role she wouldn't even have to "act" her way through—a perky television personality with a right-wing agenda—and she still made the episodes featuring J. Lo and Janet Jackson look downright Emmy-worthy. And despite sunny reports about the cast's read-through this morning (a source says Spears was "really funny" and "very professional"), TMZ is calling gimmick: