I adore this particular scene, where the Donna is trying to help the Doctor when he's poisoned--and they end up playing charades--when Donna goes, "It's a song--Mammy" like Al Jolson--my god! I thought I'd split a gut laughing. There's been a lot of funny stuff on the new Dr Who--but I have to say, that "mammy" moment has GOT to be my all-time fav.