For some reason, David Letterman had a hard time believing that Kathy Griffin could be friends with Cher. Maybe it's because Griffin always talks about how she's on the 'D-List,' but on 'Late Show' (Weeknights, 11:35PM ET on CBS) she revealed how the pair met.

It was through a mutual friend, Rosie O'Donnell, who's still above that 'D-List' herself. Griffin said she wasn't sure if she should give Cher her number, but the latter cleared that up. According to Griffin, Cher told her, "Of course you should, I'm f****** Cher."

What this might mean is that it's time for Griffin to upgrade the title of her show. Maybe it should be 'Kathy Griffin: My Life on the D-List Hanging Out With A-Listers from Time to Time.' Or, if that's too unwieldy, 'Kathy Griffin Knows Cher.' That would certainly draw some more attention toward the series.