Moo baa, double quack ,double quack is a made up phone number on the children's TV show, Hanna's Helpline. It is a number that distressed children (such as sleepwalkers and clumsy idiots) call to get Hanna to come over to help them. The number is repeated about 50 times every episode and drills into your head very quickly. Moo baa, double quack, double quack is just as deadly as Nova 6 and it is advised not to have contact with it.