SNL’s resident chameleon Bill Hader (I love his parody of Dateline’s Keith Morrison, and suddenly now he’s nailing an Alan Alda impression) was on David Letterman last night, where he explained the creation of Weekend Update’s “City Correspondent” Stefon, the effinate club kid. It seems Hader can never seem to get through the sketch without losing his cool… even though he always manages to keep cool for his other scenes… Here he gives us a little more insight…