The performers are given a basic outline of a premise by the writers, and call telephone numbers from a list of selected targets (known as "marks"). Using the basic premises, the performers improvise most of their lines, playing off of the responses of their marks, with the intention to keep them on the phone as long as possible.
With the exception of a few outside sources (including previous material from Jim Florentine and the Touch-Tone Terrorists), all the calls are made from Nevada. The Omnibus Crime Control and Safe Streets Act of 1968 makes it illegal in most states to record telephone calls without both parties' consent. Under Nevada law, only one of the parties has to give consent (i.e., the caller), so prank calls can be recorded without the consent of the prank victims. One result of this was the series' schedule of creating and airing new episodes was fairly sporadic due to most of the celebrities living in Los Angeles, having Los Angeles-based jobs, and so were only periodically able to go to Las Vegas to make calls. Adam Carolla, for example, took his radio program to Las Vegas once or twice a year, and while there would record new calls for the program.
The puppets are then constructed based on the various marks' voices, and, along with a series of stock characters (such as "Niles Standish", "Bobby Fletcher", and "Special Ed") based on the performers' character voices, the calls are re-enacted for the skits.
The main character puppets for first season were constructed by Bob Flanagan's company Den Design with additional puppets built by BJ Guyer, Carol Binion, Rick Lyon, Ron Binion, Jim Kroupa, and Artie Esposito. An in-house puppet shop was set up for the following seasons to accommodate the fast-paced schedule of the show and the sheer volume of puppet characters required for each episode.
The puppets are puppeteered by Ronald Binion, Rick Lyon, BJ Guyer, Victor Yerrid, Paul McGinnis, Alice Dinean Vernon, and Artie Esposito.
Originally, the show was titled Prank Puppets; it was renamed after Comedy Central lawyers deemed that it implied malice.
Gladys Murphy (Wanda Sykes): A boisterous black woman who makes embarrassing announcements, generally of a scatological or sexual nature. Her many children do things like gluing her buttocks to the toilet and stealing money from a malfunctioning bank machine.
Niles Standish (Tony Barbieri): The British Earl of Yankerville, he is a rich and eccentric middle-aged pervert with homosexual tendencies. He frequently calls various services and asks for their price, then orders them to "double it." (Once even confusing someone by telling them to "cut it in half, and double it!").
Special Ed (Jim Florentine): Bobby Fletcher's mentally-challenged 16-year-old younger cousin who constantly repeats himself, makes random comments, and shouts his catchphrase "Yay!" until the other caller gets frustrated. He makes a cameo in one of Bobby's prank calls, the "Let Me Put My Brother on the Phone" call. In two prank calls of his own (one to a movie theater and one to a video store), Ed reveals that his favorite movie is Air Bud. In the video-store call, he works in several references to The Shining.
Dick Birchum (Adam Carolla): A 62-year-old psychotic Vietnam War veteran whose hobbies include carpentry, Shotokan karate, spying on women in their beds or bathrooms by drilling holes or a hidden camera, and gun ownership. He has a 600-pound wife and conjoined twin daughters. He lost part of his right leg in the war and 3 right-hand fingers in a carpentry accident. He frequently refers to his time in Vietnam and "smoking hash out of a human skull."
Jimmy (Jimmy Kimmel): A Kimmel-based grown man who lives with his mother. He also has 2 young children who use foul language and play juvenile pranks.
Bobby Fletcher (Jim Florentine): Ed's drug-using underachiever older cousin. He is extremely rude and insulting, and known for generating copious amounts of gas and belching into the phone.
Elmer Higgins (Jimmy Kimmel): A crabby, long-winded stereotype of an elderly man (based on Kimmel's grandfather). He makes complaint calls and frequently goes off on unrelated, long-winded tangents about his younger days and various irrelevant subjects. He frequently blames the situations he's complaining about on his gay grandson, Terrance Catheter.
Helen Higgins (Susie Essman): Elmer's wife of over 60 years, she is an elderly Jewish woman who likes to proposition young men. Her son gave her a pet parrot who is well-versed in curse words. In a late-in-the-series sketch about Elmer wanting driving lessons, he mentions that she has died.
Landalious "The Truth" Truefeld (David Alan Grier): A former football player who likes to rap.
Spoonie Luv (Tracy Morgan): A smooth-talking African American hip hop-type character who makes lewd and suggestive comments. He often refers to himself as "Spoonie Luv from Up Above." In one particularly noteworthy prank call, he attempts to sell a video store tapes of himself masturbating.
Hadassah Guberman (Sarah Silverman): A Jewish female college student who works various part-time jobs, including conducting surveys for O magazine. She frequently asks intrusive questions and makes veiled passive-aggressive insults. Her sexuality and sanity seem highly questionable.
Tony Deloge (Bob Einstein): A loud-mouthed, fast-paced politician who calls random people to pander for votes as "district selectman." He occasionally tries to use his political power to get things for free.
Cammie Smith (Lisa Kushell): An oversexed, conceited, condescending 22-year-old exotic dancer.
Junkyard Willie (Touch-Tone Terrorists): An obstructionist in the form of a gravelly-voiced black man who is actually an import from the Touch-Tone Terrorists where he is a regular character. He appears in two sketches as a supervisor at YPS ("Yankerville Package Service").
Jim Bob the Handicapped Hillbilly (Touch-Tone Terrorists): A mentally-challenged hillbilly who works with Junkyard Willie at YPS.
Sav Macauley (Dane Cook): The overly-enthusiastic host of a phone game show, "The Phone Zone," where he calls people and asks ridiculous random trivia questions for cash prizes and interjects his own sound effects.
Danny (David Alan Grier): A man who repeatedly gets nervous or disgusted causing him to vomit over the phone. The vomit is depicted as an Exorcist-like liquid shooting out of the puppet's throat.
Chip Douglas (Fred Armisen): A Mexican immigrant who is perpetually building a house with minimal supplies and poor command of the English language. He makes two prank calls to newspaper offices, one to attempt to sell cartoons and the other (a prank call in Spanish) to inform a Spanish-language newspaper that he has not received that day's edition.
Katie (Katie Kimmel): Jimmy Kimmel's daughter made occasional appearances from 2003, initially with a few short lines but later making entire crank calls herself (notably pretending to be a drunken 9-year-old trying to order alcohol by phone).
Kevin (Kevin Kimmel): Jimmy Kimmel's son made occasional appearances from 2003, including as Elmer Higgins' grandson.
Foreign Guy (Dane Cook): A nameless immigrant who calls various places looking for assistance or to purchase something. To confuse the person he calls, he frequently switches between speaking in extremely-broken English in an incomprehensible accent to speaking fluently, with no accent. The switch is demonstrated visually by having the puppet move between the two halves of a room across a clear dividing line.
Gene Winterbuck (Dane Cook): A wheelchair-bound young man who calls libraries requesting books with titles referring to disabilities, such as "Johnny NoodleLegs".
Lou Vilman (Kevin Nealon): An easily-impressed guy who responds "Wow!" to everything.
Dick Rogers (Seth MacFarlane): A stereotypical fast-talking 1940s detective whose sketches appear in black-and-white. He'll often call to complain about issues that would make someone from the 1940s uncomfortable, such as being hit on by men at a gay bar or getting a haircut from a female hairdresser. He also calls the YMCA for help with his alcohol problem.