Knock Knock

 is a 14-year old girl in Little Lamplight in 2277.

Background
She's the twin sister of Knick Knack and changed her name from Sue to Knock Knock, because Knock Knock and Knick Knack sounded better than Knick Knack and Sue. Her role in the community is to be in charge of "morale", a job description that includes knock knock jokes and keeping the peace as an officer of the law.

She seems to have respect for the Lone Wanderer and tries to learn as many stories and jokes as she can. She found a book (Vault Boy's Big Book of Laughs for Kids) to help her with jokes, but these have since then gotten old, and she seems to want to know more.

Daily schedule
Knock Knock wanders around Little Lamplight all day until she goes to sleep.

Quest: Tales of the Wastes
If you ask her for a joke and laughs at it or pretends they found it funny, she will ask the Lone Wanderer for tales from the Wasteland.

Basically, there are three parts of "your story" you can tell her depending on progress in the main story. No matter where the Lone Wanderer is in the main quest, she can be told the first stage, about exiting the vault. After completing The Waters of Life, the Lone Wanderer relays James's sacrifice. The final part of the story details the escape from the Enclave in The American Dream.

No matter your Karma, you can tell her 3 versions of your story: good, neutral and evil. Whatever you tell her she will proceed to tell to every other Lamplighter she comes across.

Knock Knock is an essential NPC.

Quotes
''This is an A-B conversation, you know... you can "C" your way out of it.''

''Knock knock? Who's there? Noah? Noah Who? Noah place where I can get something to eat?''

Appearances
appears only in Fallout 3.

Bugs

 * Exploit: If you keep asking her for her jokes and lie that they're funny, you get additional xp each time this is performed.
 * The bug mentioned above may also be used to obtain the achievment/trophy Silver-Tongued Devil (50 speech successes)