Knock Knock

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

Background
She's the twin sister of Knick Knack and changed her name from Sue to Knock Knock as Knock Knock and Knick Knack sounded better than Knick Knack and Sue. Her name likely stems from her aptitude for jokes (i.e. knock knock jokes). 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 Jokes) to help her with jokes, but these have since then gotten old, and she seems to want to know more.

Interactions with the player character
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.

Quotes

 *  This is an A-B conversation, you know... you can "C" your way out of it. (While in conversation)

Appearances
Knock Knock appears in Fallout 3.

Behind the scenes
-Chris: Fool, I wasn't even talking to you. This is a A-B conversation, you know... you can "C" your way out of it. Doughboy: Yeah, you can "C" your way out my ride, and we'll "C" your cripple ass walking all the way home.
 * Knock Knock's quote of '"C" Your way out' originates from a Gangster based Ghetto filmed of Boyz n the Hood  in which the main character Chris and Doughboy are arguing:

Bugs

 * If you keep asking her for her jokes, and lie that they're funny, you get additional exp each time this is performed.