Roseanne Barr told
David Letterman on "
Late Show" (Weeknights, 11:35 p.m. ET on CBS) that she agreed to do a
Comedy Central Roast because the network said they wanted their next celebrity target to provide a "classy" roast. And that was just the tip of the iceberg, as the opinionated comedienne was all over the place during her appearance.She ranted about medical marijuana, railing against the president. "
Obama, you'll get my joint when you ...